Đề thi thử ACT (Enhanced) số 2: ACT Mock Test 2

English (35 phút)

Passage I

Each numbered portion of the passage is underlined. For each question, choose the option that makes that portion correct, clear and consistent with the style of the passage. Choose NO CHANGE if the original is best. Some questions ask about a whole sentence or about the passage as a whole.

Bees Above the Avenue

On the roof of a nine-story hotel in downtown Chicago, Marisol Ortega lifts the lid of a white wooden box and peers inside. Forty thousand honeybees crawls across the frames, ignoring the traffic noise rising from the street below. Ortega who manages the hotel's six hives says that most guests are surprised to learn that the honey on their breakfast tray was made on the roof above them.

Urban beekeeping can seem like a contradiction. Cities are crowded with concrete, glass, and asphalt, so they also contain a surprising variety of flowering plants. Street trees such as lindens and honey locusts bloom in early summer, and the window boxes, community gardens, and vacant lots of a large city offer a steady supply of nectar from spring until frost. In fact, some researchers have found that city bees collect pollen from more kinds of plants than bees living near large farms, where a single crop may cover thousands of acres.

Still, keeping bees on a rooftop is not as simple as setting a box in the sun. Wind is the biggest problem. At ground level, buildings block much of the wind, but on an open roof a strong gust can knock over a hive or chill the bees inside. Ortega straps each hive to a steel frame bolted to the roof, she also places a low wall of planters on the windward side. Water is another concern. Bees need to drink, and a colony on a hot roof can use more than a quart of water a day. Without a nearby source, the bees will search for one, flying in many directions.

Despite these challenges, the number of registered hives in Chicago have more than doubled over the past decade. Ortega thinks the appeal goes beyond honey. "Up here, people stop looking at their phones," she says. "They watch the bees come and go, and for a few minutes they remember that the city is part of the natural world, not separate from it."

1. Underlined portion [1]: "crawls"
   • NO CHANGE
   • crawl
   • is crawling
   • has crawled
2. Underlined portion [2]: " who manages the hotel's six hives says"
   • NO CHANGE
   • , who manages the hotel's six hives says
   • who manages, the hotel's six hives, says
   • , who manages the hotel's six hives, says
3. Underlined portion [3]: "so"
   • NO CHANGE
   • but
   • because
   • therefore
4. Underlined portion [4]: "offer"
   • NO CHANGE
   • offers
   • is offering
   • has offered
5. The writer is considering deleting sentence [5]. Should the sentence be kept or deleted?
   • Deleted, because it shifts the focus of the paragraph from cities to farms.
   • Kept, because it explains how farmers decide which crops to plant.
   • Kept, because it gives evidence that supports the paragraph's claim that cities can offer bees a variety of plants.
   • Deleted, because it contradicts the claim that cities are crowded with concrete.
6. Underlined portion [6]: "knock over"
   • NO CHANGE
   • overthrow
   • defeat
   • upset into
7. Underlined portion [7]: "bolted to the roof, she also"
   • NO CHANGE
   • bolted to the roof she also
   • bolted to the roof, also she
   • bolted to the roof; she also
8. Underlined portion [8]: "flying in many directions". Which choice most clearly shows how a missing water source can affect people who live near the hotel?
   • NO CHANGE
   • often during the hottest hours of the day
   • sometimes in a neighbor's swimming pool or birdbath
   • usually within a short distance of the hive
9. Underlined portion [9]: "have more than doubled"
   • NO CHANGE
   • has more than doubled
   • more than doubling
   • having more than doubled
10. Suppose the writer's goal had been to explain the steps a beginner must follow to get a beekeeping permit in Chicago. Would this essay accomplish that goal?
    • Yes, because it describes the rules Ortega follows when she places her hives.
    • Yes, because it mentions that the number of registered hives has grown.
    • No, because it focuses instead on the challenges and appeal of keeping bees on a city rooftop.
    • No, because it argues that cities are poor places to keep bees.

Passage II

Each numbered portion of the passage is underlined. For each question, choose the option that makes that portion correct, clear and consistent with the style of the passage. Choose NO CHANGE if the original is best. Some questions ask about a whole sentence or about the passage as a whole.

The Lens That Bent the Dark

Before the 1820s, most lighthouses relied on a design, that had changed little in a century: oil lamps placed in front of curved metal mirrors. The mirrors reflected some of the light toward the sea, but much of it was lost, absorbed by the dull metal or scattered upward into the sky above. On a clear night, a ship's lookout might see such a light from fifteen or twenty miles away. In fog, the light might disappear entirely.

The French physicist Augustin Fresnel, who had been studying the behavior of light waves, he proposed a different approach in 1822. Instead of one large glass lens, which would have been too heavy and thick to make, he designed a lens built from many rings of glass arranged around a center. Each ring was shaped to bend light at a slightly different angle, so that the rings worked together like a single, much thicker lens. Surrounding the central rings were glass prisms that caught light escaping above and below the lamp and redirected it toward the horizon.

The results were dramatic. A first-order Fresnel lens, the largest size, could gather most of a lamp's light into a beam, and that beam could be seen from much farther away. The lenses were expensive, and each one had to be ground and polished by hand. Despite the cost, governments on both sides of the Atlantic began installing them. By the time the American Civil War began in 1861, nearly every lighthouse on the coast of the United States has been fitted with one.

Today, many lighthouses use small electric beacons, and the great glass lenses have been moved into museums. Visitors who stand beside one often describes it as a sculpture rather than a machine. Its hundreds of glass pieces catch the light from every angle, scattering small rainbows across the walls. Yet each piece was placed for a purpose: to send a lamp's glow as far into the dark as possible, giving sailors a fixed point they could trust.

1. Underlined portion [11]: ", that had changed little in a century"
   • NO CHANGE
   • that had changed little in a century
   • , that, had changed little in a century
   • that, had changed little, in a century
2. Underlined portion [12]: "upward into the sky above"
   • NO CHANGE
   • upward above into the sky
   • into the sky
   • up above, skyward,
3. Underlined portion [13]: "waves, he proposed"
   • NO CHANGE
   • waves; proposed
   • waves, and proposing
   • waves, proposed
4. Underlined portion [14]: "redirected it"
   • NO CHANGE
   • redirected them
   • redirecting it
   • was redirected
5. Underlined portion [15]: "much farther away". Given that all the choices are accurate, which one gives the most specific information about the improvement the lens made?
   • NO CHANGE
   • a greater distance than before
   • more than twenty miles away, even in light haze
   • places the old lights could not reach
6. Underlined portion [16]: "Despite"
   • NO CHANGE
   • Because of
   • Due to
   • Thanks to
7. Underlined portion [17]: "has been fitted"
   • NO CHANGE
   • had been fitted
   • will have been fitted
   • fits
8. Underlined portion [18]: "often describes it as"
   • NO CHANGE
   • often describing it as
   • is often describing it like
   • often describe it as
9. The writer is considering deleting sentence [19]. Should the sentence be kept or deleted?
   • Deleted, because it repeats information about how the lens bends light.
   • Deleted, because it distracts from the essay's focus on lighthouse keepers.
   • Kept, because it adds a visual detail that supports the comparison of the lens to a sculpture.
   • Kept, because it explains why the lenses were moved into museums.
10. Underlined portion [20]: "possible, giving"
    • NO CHANGE
    • possible. Giving
    • possible; giving
    • possible, it gave

Passage III

Each numbered portion of the passage is underlined. For each question, choose the option that makes that portion correct, clear and consistent with the style of the passage. Choose NO CHANGE if the original is best. Some questions ask about a whole sentence or about the passage as a whole.

The Pond Behind My Grandfather's House

Every summer of my childhood, my parents sent me from Houston to spend two months with my grandfather in a village outside Hanoi. He was a quiet man, he spoke little at dinner, but in the evenings he disappeared into a shed behind the house, and I could hear him sawing and sanding until long after dark. I was nine before I learned what he was making.

My grandfather was a puppet maker for the village's water puppet troupe. Water puppetry, or múa rối nước, is a Vietnamese art that dates back nearly a thousand years ago in the past. The puppeteers stand waist-deep in a pond, hidden behind a bamboo screen, and they move the wooden figures with long poles and strings that run beneath the surface of the water. To the audience, the dragons, farmers, and ducks seem to glide across the water on their own.

The puppets themselves is made from the wood of the fig tree, which is light enough to float and soft enough to carve. My grandfather showed me how to rough out a figure with a hatchet, then refine it's features with a small knife. Once the carving was done, he coated each puppet with several layers of lacquer in order to keep the water out from getting in. A single dragon might take him a month to finish.

That summer, I asked if I could make a puppet of my own. My grandfather handed me a block of fig wood and said nothing else. I spent three weeks on a small duck, and when it was finished, it is lopsided, with one wing noticeably larger than the other. I expected him to laugh. Instead, he took it to the pond, set it on the water, and watched it float. "It swims," he said, which, from him was high praise.

My grandfather died when I was in college. Faded and cracked, I keep the duck on a shelf in my apartment in Houston. When friends ask about it, I tell them about the pond, the bamboo screen, and the quiet man who taught me that a thing does not have to be perfect to do what it was made to do.

1. Underlined portion [21]: "He was a quiet man, he spoke little"
   • NO CHANGE
   • He was a quiet man who spoke little
   • He was a quiet man; speaking little
   • Being a quiet man, speaking little
2. Underlined portion [22]: "dates back nearly a thousand years ago in the past"
   • NO CHANGE
   • dates back in the past nearly a thousand years ago
   • is dating back previously nearly a thousand years
   • dates back nearly a thousand years
3. Underlined portion [23]: "that run beneath the surface of the water". Which choice best explains why the puppets seem to move on their own?
   • NO CHANGE
   • made of bamboo and twine
   • that the puppeteers have used for years
   • that are sold at the village market
4. Underlined portion [24]: "themselves is made"
   • NO CHANGE
   • itself is made
   • themselves are made
   • theirselves are made
5. Underlined portion [25]: "it's"
   • NO CHANGE
   • it is
   • their
   • its
6. Underlined portion [26]: "in order to keep the water out from getting in"
   • NO CHANGE
   • for keeping the water from out
   • to keep the water out
   • so that water, it would not get in
7. Underlined portion [27]: "is"
   • NO CHANGE
   • was
   • has been
   • will be
8. Underlined portion [28]: "which, from him was high praise."
   • NO CHANGE
   • which from him, was high praise.
   • which, from him, was high praise.
   • that, from him, was high praise.
9. Underlined portion [29]: "Faded and cracked, I keep the duck on a shelf"
   • NO CHANGE
   • Faded and cracked, the duck sits on a shelf
   • Faded and cracked, a shelf holds the duck
   • Faded and cracked, my apartment has the duck on a shelf
10. Underlined portion [30]: "do what it was made to do". Which choice most effectively ends the essay by echoing the grandfather's words about the duck?
    • NO CHANGE
    • be sold at a market
    • look exactly like a real duck
    • impress a large audience

Passage IV

Each numbered portion of the passage is underlined. For each question, choose the option that makes that portion correct, clear and consistent with the style of the passage. Choose NO CHANGE if the original is best. Some questions ask about a whole sentence or about the passage as a whole.

Mapping in the Dark

Most maps begin with a view from above: an aerial photograph, a satellite image, or a surveyor's sight line across open ground. Cave maps cannot. Underground, there is no sky to photograph and no horizon to sight on. Every measurement must be taken by people who crawl, climb, and sometimes swim through the passages they are drawing.

A typical survey team has three members. The first, called the lead, moves ahead and chose a survey station, usually a rock or ledge that can be found again. The second member holds one end of a measuring tape at the previous station while the lead stretches the other end to the new one. Using a compass and a clinometer, an instrument that measures the angle of a slope, the distance, direction, and slope of each segment are recorded by the team. The third member, the sketcher, draws the walls, floor, and ceiling of the passage around each segment.

The work is slow. In a tight passage, a team may survey only a few hundred feet in a full day. Moreover, the results can be remarkably precise. When a team closes a loop, returning by a different route to a station it measured earlier, the total error is often less than one percent of the loop's length, even after thousands of feet of measurements, each one taken by hand.

Survey data has uses, which are practical, that go well beyond exploration. Because caves often carry groundwater, maps help hydrologists track how pollution travel from the surface into wells and springs. Engineers who plan roads and buildings in limestone regions also rely on cave maps to avoid building over hollow ground that might collapse.

In recent years, some teams have begun to use handheld laser scanners that record millions of points in a few minutes. The scanners produce detailed three-dimensional models, and the models can be viewed on a computer screen. For now, most cave maps are still made the old way, one tape length at a time, by people who's patience matches their curiosity.

1. Underlined portion [31]: "sight on. Every"
   • NO CHANGE
   • sight on, every
   • sight on every
   • sight on; and every
2. Underlined portion [32]: "moves ahead and chose"
   • NO CHANGE
   • moved ahead and choosing
   • moves ahead and chooses
   • moving ahead and chooses
3. Underlined portion [33]: "the distance, direction, and slope of each segment are recorded by the team."
   • NO CHANGE
   • the team records the distance, direction, and slope of each segment.
   • the distance, direction, and slope of each segment is recorded.
   • recording the distance, direction, and slope of each segment by the team.
4. Underlined portion [34]: "Moreover,"
   • NO CHANGE
   • However,
   • Therefore,
   • For example,
5. Underlined portion [35]: "measurements, each one taken"
   • NO CHANGE
   • measurements, each one was taken
   • measurements each one taken,
   • measurements; each one taken
6. Underlined portion [36]: "has uses, which are practical, that go well beyond"
   • NO CHANGE
   • has uses that are practical and that go beyond, well,
   • has, practically, uses going well beyond
   • has practical uses that go well beyond
7. Underlined portion [37]: "travel"
   • NO CHANGE
   • have traveled
   • travels
   • are traveling
8. The writer is considering adding the following sentence after sentence [38]: "Limestone is a sedimentary rock made mostly of calcium carbonate." Should the writer make this addition?
   • Yes, because it explains why caves form in limestone.
   • Yes, because it identifies the engineers who use cave maps.
   • No, because it gives a definition that does not support the paragraph's point about the uses of cave maps.
   • No, because it contradicts the claim that caves carry groundwater.
9. Underlined portion [39]: "and the models can be viewed on a computer screen". Which choice best sets up the next sentence's point that most cave maps are still made the old way?
   • NO CHANGE
   • but they are heavy, expensive, and easily damaged by mud and water
   • and they have been praised in several science magazines
   • and they can be used in buildings as well as caves
10. Underlined portion [40]: "who's"
    • NO CHANGE
    • whose
    • who is
    • whom

Passage V

Each numbered portion of the passage is underlined. For each question, choose the option that makes that portion correct, clear and consistent with the style of the passage. Choose NO CHANGE if the original is best. Some questions ask about a whole sentence or about the passage as a whole.

The Overnight Voice

At two o'clock in the morning, the studio of WRKB, a small community radio station in western Montana, is lit by a single desk lamp and the green glow of the mixing board. Ellen Tsosie has hosted the station's overnight program for eleven years. Her listeners include truck drivers, nurses on break, and ranchers checking on calving cows, many of who she has never met. Some of them have been listening since her first night on the air.

Overnight radio has a different rhythm from daytime broadcasting. There are fewer commercials, and the station's automated system, which plays music during unstaffed hours, are turned off while Tsosie is on the air. She chooses every song herself, and she often follows a listener's request with a long stretch of instrumental music. "At this hour, people want company," she explains, "not noise." She keeps a notebook of requests and the names of regular callers, and she tries to remember whose birthday is coming up.

The job also carries a responsibility that daytime hosts rarely face. In 2019, a wildfire spread toward a town in the station's listening area shortly after midnight. The fire moved faster than anyone had predicted, pushed by strong winds out of the west. Cell service in the valley had failed, and many residents were asleep. Tsosie had worked through many long nights before. Afterward, several families told her that the broadcast had been the only reason they knew to leave. No one in the town was hurt.

Stations like WRKB depends on volunteers and listener donations. WRKB has only three paid employees, and its transmitter was bought with money raised at a single spring pledge drive. Tsosie is paid for twenty hours a week, because she usually works closer to forty. She does not mind. Sometimes, near dawn, a caller phones in just to say good morning, and she knows that somewhere on a dark highway or in a lit kitchen, someone has been listening the whole time.

1. Underlined portion [41]: "is lit by"
   • NO CHANGE
   • are lit by
   • lighting by
   • being lit by
2. Underlined portion [42]: "many of who"
   • NO CHANGE
   • many of whom
   • many of them
   • many whom
3. Underlined portion [43]: "are turned off"
   • NO CHANGE
   • turning off
   • is turned off
   • having been turned off
4. Underlined portion [44]: "herself, and she"
   • NO CHANGE
   • herself, she
   • herself and, she
   • herself; and she
5. Underlined portion [45]: "had failed, and"
   • NO CHANGE
   • had failed and,
   • had failed, many
   • having failed, and
6. Underlined portion [46]: "Tsosie had worked through many long nights before.". Which choice most effectively shows how Tsosie's program helped residents during the emergency?
   • NO CHANGE
   • The station's transmitter was located on a hill above the valley.
   • Wildfires are common in western Montana in late summer.
   • For six hours, Tsosie read evacuation updates from the county sheriff's office, repeating road closures every few minutes.
7. Underlined portion [47]: "depends"
   • NO CHANGE
   • is depending
   • depend
   • has depended
8. Underlined portion [48]: "because"
   • NO CHANGE
   • though
   • so
   • since
9. The writer is considering deleting sentence [49]. Should the sentence be kept or deleted?
   • Kept, because it explains how the station raises money from listeners.
   • Deleted, because it contradicts the idea that the job is demanding.
   • Deleted, because it repeats information from the previous paragraph.
   • Kept, because it shows Tsosie's attitude toward the extra hours, which the next sentence helps explain.
10. Suppose the writer's goal had been to describe what a community radio host's job involves and why it matters to listeners. Would this essay accomplish that goal?
    • No, because it focuses mainly on the history of WRKB.
    • Yes, because it describes Tsosie's choices on the air, her role during an emergency, and her bond with listeners.
    • Yes, because it compares the salaries of daytime and overnight hosts.
    • No, because it describes only the wildfire of 2019.

Math (50 phút)

Mathematics

Choose the best answer for each problem. A calculator is allowed. Figures are not drawn to scale unless a problem says so, and all numbers are real unless a problem says otherwise.

1. What is the value of 20 - 3(4 - 9)?
   • -85
   • -1
   • 5
   • 35
2. Mara spent 1/4 of her savings on a bike helmet and 1/3 of her savings on a lock. What fraction of her savings did she have left?
   • 2/7
   • 5/12
   • 7/12
   • 5/7
3. On weekday mornings, buses on Route 4 leave the depot every 12 minutes and buses on Route 9 leave every 18 minutes. One bus on each route leaves the depot at 7:00 a.m. What is the next time that buses on both routes leave the depot together?
   • 7:06 a.m.
   • 7:30 a.m.
   • 7:36 a.m.
   • 10:36 a.m.
4. On a hiking map, 2 centimeters represent 15 kilometers. Two campsites are 9 centimeters apart on the map. What is the actual distance between the campsites, in kilometers?
   • 1.2
   • 30
   • 67.5
   • 135
5. A 12-ounce bottle of shampoo costs $4.80, and a 20-ounce bottle of the same shampoo costs $7.00. How many cents less per ounce does the 20-ounce bottle cost than the 12-ounce bottle?
   • 5
   • 27.5
   • 35
   • 40
6. The sum of three consecutive even integers is 78. What is the greatest of the three integers?
   • 24
   • 26
   • 27
   • 28
7. In the standard (x,y) coordinate plane, at what point does the graph of 3x - 4y = 24 cross the x-axis?
   • (0, -6)
   • (6, 0)
   • (-8, 0)
   • (8, 0)
8. A school has 800 students. Of these, 35% ride a bus to school, and 1/4 of the students who do not ride a bus walk to school. How many students walk to school?
   • 130
   • 200
   • 390
   • 520
9. A phone plan charges $15 per month plus $0.10 for each text message after the first 200 text messages in that month. Which of the following expressions gives the charge, in dollars, for a month with t text messages, where t > 200?
   • 15 + 0.10t
   • 15 + 0.10(t + 200)
   • 15 + 0.10(t - 200)
   • 0.10(15 + t - 200)
10. A plumber charges a $50 fee for each visit plus $40 for each hour of work. A customer's bill for one visit was $230. How many hours did the plumber work?
    • 3.5
    • 4.5
    • 5.75
    • 7
11. In triangle PQR, the exterior angle at vertex R measures 130 degrees, and angle P measures 55 degrees. What is the measure of angle Q?
    • 50 degrees
    • 55 degrees
    • 65 degrees
    • 75 degrees
12. In a survey, 20 students reported how many pets they have: 4 students have 0 pets, 7 have 1 pet, 6 have 2 pets, and 3 have 3 pets. What is the mean number of pets per student?
    • 1
    • 1.4
    • 1.5
    • 5
13. Jun has $50. He buys a concert ticket for $14 and wants to spend the rest of his money on snacks that cost $3.50 each. What is the greatest number of snacks he can buy?
    • 10
    • 11
    • 14
    • 18
14. What value of n satisfies the equation n/4 + n/6 = 5?
    • 12
    • 25
    • 50
    • 60
15. Which of the following is equal to (6.0 x 10^5)(4.0 x 10^-2)?
    • 2.4 x 10^3
    • 2.4 x 10^7
    • 1.5 x 10^7
    • 2.4 x 10^4
16. In the standard (x,y) coordinate plane, point M(3, -2) is the midpoint of segment AB, and point A has coordinates (-1, 4). What are the coordinates of point B?
    • (7, -8)
    • (1, 1)
    • (4, -6)
    • (-5, 10)
17. A trapezoid has parallel sides of lengths 10 inches and 16 inches, and the distance between the parallel sides is 7 inches. What is the area of the trapezoid, in square inches?
    • 45.5
    • 56
    • 70
    • 91
18. Which of the following is equivalent to (x + 4)(x - 4) - x(x - 2)?
    • -2x - 16
    • 2x + 16
    • 2x - 16
    • 2x^2 - 2x - 16
19. If (x + 2)/5 = (x - 1)/3, what is the value of x?
    • -5.5
    • 1.5
    • 3.5
    • 5.5
20. The formula F = (9/5)C + 32 converts a temperature of C degrees Celsius to F degrees Fahrenheit. Which of the following expresses C in terms of F?
    • C = (5/9)F - 32
    • C = (9/5)(F - 32)
    • C = (5/9)(F + 32)
    • C = (5/9)(F - 32)
21. In a club of 40 students, 22 play chess, 15 play go, and 7 play both games. How many students in the club play neither game?
    • 3
    • 7
    • 8
    • 10
22. The height h, in centimeters, of a bean plant t days after it was first measured is modeled by the equation h = 0.75t + 32. What does 0.75 represent in this model?
    • The number of centimeters the plant grows each day
    • The height of the plant, in centimeters, when it was first measured
    • The number of days the plant takes to grow 32 centimeters
    • The height of the plant, in centimeters, one day after it was measured
23. Lines m and n are parallel and are cut by transversal t. Two same-side interior angles formed by these lines measure (3x + 10) degrees and (5x - 6) degrees. What is the value of x?
    • 8
    • 20.5
    • 22
    • 23
24. A linear function f satisfies f(2) = 11 and f(6) = 23. What is the value of f(13)?
    • 33
    • 39
    • 44
    • 71.5
25. Each exterior angle of a regular polygon measures 24 degrees. How many sides does the polygon have?
    • 7.5
    • 13
    • 15
    • 17
26. The number of hours a crew needs to paint a fence varies inversely with the number of painters in the crew. With 5 painters, the job takes 12 hours. How many hours would the job take with 15 painters working at the same rate?
    • 4
    • 22
    • 36
    • 60
27. For a group of students, the line of best fit relating exam score y to hours studied x is y = 2.5x + 40. A student who studied for 8 hours scored 66. What is the residual for this student (actual score minus predicted score)?
    • -6
    • 6
    • 26
    • 60
28. What is the solution of the equation 4/x + 1/3 = 1?
    • 2
    • 3
    • 6
    • 12
29. A cube has a total surface area of 150 square inches. What is the volume of the cube, in cubic inches?
    • 25
    • 125
    • 625
    • 15,625
30. In the standard (x,y) coordinate plane, what are the x-intercepts of the graph of y = (x - 3)(2x + 5)?
    • x = -3 and x = 5/2
    • x = 3 and x = -5
    • x = 3 and x = -5/2
    • x = 3 and x = 5/2
31. The graph of y = g(x) is translated 3 units to the left and 2 units down. Which of the following is an equation of the new graph?
    • y = g(x - 3) - 2
    • y = g(x + 3) + 2
    • y = g(x - 2) + 3
    • y = g(x + 3) - 2
32. Points A, B, and C lie on a circle. The arc AB that does not contain point C measures 110 degrees. What is the measure of inscribed angle ACB?
    • 55 degrees
    • 70 degrees
    • 110 degrees
    • 125 degrees
33. A drawer holds 5 black socks and 3 white socks. Two socks are taken out at random, one after the other, without replacement. What is the probability that both socks are black?
    • 3/28
    • 5/14
    • 25/64
    • 5/8
34. If 9^x = 27, what is the value of x?
    • 2/3
    • 3/2
    • 3
    • 18
35. The value V, in dollars, of a used car t years after it was bought is modeled by V = 24,000(0.85)^t. Which of the following statements about the model is true?
    • The value drops by 85% of the previous year's value each year.
    • The value drops by 15% of the previous year's value each year.
    • The value drops by $3,600 every year.
    • The car is worth $20,400 less after one year than when it was bought.
36. Two triangles are similar, and the ratio of their corresponding side lengths is 2:5. The area of the smaller triangle is 12 square centimeters. What is the area of the larger triangle, in square centimeters?
    • 30
    • 48
    • 60
    • 75
37. How many real solutions does the equation 2x^2 - 4x + 5 = 0 have?
    • 0
    • 1
    • 2
    • Infinitely many
38. What is the value of log_2(40) - log_2(5)?
    • 3
    • 8
    • 35
    • log_2(35)
39. For what value of k does the system of equations 2x + 3y = 7 and kx + 6y = 5 have no solution?
    • -4
    • 2
    • 4
    • 6
40. A circle is drawn inside a square with side length 10 so that the circle touches all four sides of the square. A point inside the square is chosen at random. What is the probability that the point lies inside the circle?
    • 1/4
    • pi/10
    • pi/4
    • pi/2
41. What are all the real solutions of the equation sqrt(2x + 3) = x?
    • x = 3 only
    • x = -1 only
    • x = 3 or x = -1
    • No real solution
42. If x - 2 is a factor of the polynomial x^3 + kx^2 - 5x + 6, what is the value of k?
    • -2
    • -1
    • 1
    • 2
43. What is the period of the function y = 3sin(4x)?
    • pi/4
    • pi/2
    • 3
    • 8pi
44. For all x such that sin x and cos x are not 0, which of the following is equivalent to (1 - cos^2 x)/(sin x cos x)?
    • cot x
    • sin x
    • 1/cos x
    • tan x
45. In triangle ABC, AB = 7, AC = 5, and the measure of angle A is 60 degrees. What is the length of BC? (Note: For a triangle with sides of lengths a, b, and c, where angle C is opposite the side of length c, c^2 = a^2 + b^2 - 2ab cos C.)
    • 2
    • sqrt(39)
    • sqrt(74)
    • sqrt(109)

Reading (40 phút)

Passage I

Literary Narrative. Read the passage and choose the best answer to each question. Answer on the basis of what the passage states or implies.

LITERARY NARRATIVE: This passage is from a short story about a family that runs a tailoring shop in California.

The bell over the door of Tran Alterations rang so often on Saturdays that Linh had stopped hearing it by the age of twelve. Now, at seventeen, she heard it only when she was waiting for someone, and this morning she was waiting for the mail.

She sat at the cutting table at the back of the shop, pinning the hem of a bridesmaid's dress the color of canned peaches. Her mother worked at the machine by the window, where the light was best. Má did not use the pedal so much as speak to it, a quick, steady pressure that made the needle sound like rain on a tin roof. Twenty-two years of hems and zippers and taken-in waists had passed under that needle, and Linh had never once seen it jam.

"Straight pins, not safety pins," Má said without looking up. "The bride's sister is coming at two."

"I know."

"You know, but your pins are crooked."

Linh pulled out the last three pins and put them back in. It was easier than arguing, and she had learned long ago that her mother could see a crooked pin from across a room the way other mothers could see a lie.

The letter she was waiting for would come from an art school in New York, a place her parents referred to, when they referred to it at all, as "that school," the way they might have spoken of a cousin who had moved away and stopped calling. Her father had driven her to the portfolio review in San Francisco without saying a word for forty miles. On the way home he had asked only whether they had fed her lunch.

It was not that her parents disapproved of drawing. Her father had framed a pencil sketch she made of the shop at age ten, and it still hung beside the register, slightly yellowed, between the business license and a calendar from the Vietnamese grocery down the street. What they disapproved of was distance. They had crossed an ocean once, in 1991, with Linh's grandmother and two suitcases, and as far as they were concerned that was enough crossing for one family.

At eleven-thirty the bell rang again, and it was the mail carrier, a tall man named Ruben who always said "Buenos días, señora" to Má, and to whom Má always answered "Good morning," as if they were trading something. He set a stack of envelopes on the counter. Linh made herself finish pinning the hem before she walked over.

The envelope was thick. She knew what that meant; everyone knew what that meant. She held it without opening it, and for a moment the only sound in the shop was the needle.

"Open it," Má said.

Linh looked up. Her mother had stopped sewing. Linh could not remember the last time she had seen the machine sit still in the middle of the morning.

She opened it. She read the first line twice, because the first time the words did not seem to be in any particular order. Then she said, "I got in," and was surprised at how small her voice sounded.

Má nodded slowly. She stood, wiped her hands on the cloth she kept tucked in her apron, and went to the back of the shop, to the tall cabinet where she kept the fabrics too good to use on ordinary customers. Linh assumed she was going to hide there, the way she sometimes did after an argument with Linh's father, rearranging bolts of silk until her face was arranged again.

Instead she came back with a folder. Its corners were soft, and the cardboard had faded from blue to the gray of old denim. Má set it on the cutting table and opened it.

Inside were drawings, dozens of them, on thin paper that had once been pages of a ledger. They were designs for áo dài, the long tunic Linh had worn exactly twice, at her cousins' weddings. But these were not like any áo dài Linh had seen. One had a collar that rose like a lotus bud; another had sleeves split at the elbow and edged with a pattern of tiny boats.

"I made these in Đà Nẵng," Má said. "Before. I wanted to go to the design school in Saigon. My father said a girl who could sew did not need a school to teach her to sew."

Linh turned the pages. The lines were confident, quick, unerased. They looked like her own.

"Why didn't you tell me?"

Her mother shrugged, a small movement, mostly in one shoulder. "You did not need to know until you needed to know." She closed the folder and slid it across the table. "Now you need to know."

Then she went back to the machine, and the needle began again, and Linh stood holding the envelope in one hand and the folder in the other, listening to the rain on the tin roof.

1. Which of the following best describes what happens in the passage?
   • A girl argues with her father about which college she should attend.
   • A girl's acceptance to an art school leads her mother to reveal part of her own past.
   • A family decides to close its tailoring shop and move to New York.
   • A mother teaches her daughter how to design traditional clothing.
2. The statement that Má "did not use the pedal so much as speak to it" mainly suggests that Má:
   • operates the sewing machine with ease and skill built over many years.
   • talks to her sewing machine when she is alone in the shop.
   • finds the noise of the old machine unpleasant.
   • is impatient because the machine often breaks down.
3. Based on the passage, Linh's parents' attitude toward the school in New York is best described as:
   • open anger that they express in frequent arguments.
   • enthusiastic support that they hide from relatives.
   • quiet reluctance that comes mainly from not wanting the family to be separated.
   • indifference, because they do not think drawing has any value.
4. The detail about the framed pencil sketch beside the register mainly serves to show that Linh's parents:
   • plan to sell Linh's drawings to customers.
   • want Linh to take over the shop someday.
   • have forgotten about Linh's interest in art.
   • do value Linh's drawing, even though they dislike the idea of her leaving.
5. According to Má, she did not attend the design school in Saigon because:
   • her father believed that a girl who could already sew did not need such a school.
   • the family left Vietnam before the school year began.
   • she could not afford the cost of the school.
   • she failed the school's entrance review.
6. When Má walks to the cabinet, Linh first assumes that her mother is going to:
   • choose a fabric for the bridesmaid's dress.
   • find a gift to celebrate Linh's acceptance.
   • compose herself privately, as she sometimes does after an argument.
   • put away the mail that Ruben delivered.
7. The description of the folder's soft corners and faded cardboard most strongly suggests that the folder:
   • was recently bought for Linh's school applications.
   • has been kept for a very long time.
   • belongs to one of the shop's customers.
   • was damaged during the family's trip in 1991.
8. When Linh notices that the lines of the drawings "looked like her own," she is most likely realizing that:
   • her mother copied Linh's sketches without asking.
   • she and her mother share a similar talent and way of drawing.
   • the drawings were made by Linh when she was younger.
   • her mother wants Linh to become a tailor instead of an artist.
9. The final reference to "the rain on the tin roof" mainly serves to:
   • suggest that a storm has begun outside the shop.
   • show that Linh is still too nervous to think clearly.
   • contrast the noise of the shop with the quiet of New York.
   • echo an earlier image of the sewing machine, signaling that the shop's routine has resumed.

Passage II

Social Science. Read the passage and choose the best answer to each question. Answer on the basis of what the passage states or implies.

SOCIAL SCIENCE: This passage is adapted from an essay about lending libraries that loan objects rather than books.

In a converted storefront in a mid-sized American city, a woman returns a carpet cleaner, a man checks out a ladder and a tile saw, and a teenager asks whether anyone has brought back the sewing machine yet. The room looks like a hardware store, but nothing here is for sale. It is a library, and its collection consists of things.

Libraries of things, as they have come to be called, lend objects the way traditional libraries lend books: tools, camping gear, kitchen appliances, musical instruments, even cake pans shaped like cartoon characters. One of the earliest, a tool lending library run by the public library in Berkeley, California, opened in 1979. For decades it remained something of a curiosity. Since around 2010, however, hundreds of similar collections have appeared across North America, Europe, and Australia, some inside public library branches and others run by nonprofit groups that charge a modest yearly membership fee.

Supporters often explain the appeal with a simple economic argument. Many household objects spend nearly all of their existence doing nothing. A widely repeated claim holds that the average electric drill is used for only thirteen minutes in its entire lifetime. The figure is difficult to trace to any actual study, and it is probably too low, but the point behind it is reasonable. Economists call this idle capacity: a resource that could be producing value but is sitting unused. When dozens of households share a single drill, each one gains access to the tool at a small fraction of the cost of owning it, and the drill itself finally gets some work.

If the argument is so simple, it is fair to ask why sharing did not become common long ago. Part of the answer lies in what economists call transaction costs, the time and effort it takes to arrange an exchange. Borrowing a ladder from a neighbor requires knowing which neighbor owns one, asking a favor, and returning the ladder in good condition, all of which carry social as well as practical costs. A library of things lowers those costs by making the exchange impersonal and predictable. Borrowers do not have to wonder whether they are imposing; they simply check an item out, as they would a novel.

The early evidence suggests that the model can work, though not always in the ways its founders expected. Many organizers assumed that their biggest problem would be theft or damage. In practice, most report that losses are small, often less than two percent of the collection in a given year. The harder problem turned out to be demand that arrives all at once. Pressure washers and lawn aerators sit on the shelf all winter, then are reserved for weeks in advance as soon as the weather warms. A library that buys enough aerators to satisfy April will have a storeroom full of idle aerators in November, which is precisely the problem the library was meant to solve.

There are also questions about who benefits. A study of several lending libraries in one region found that their most frequent users tended to be homeowners with cars, people who had both projects to do and a way to carry a table saw home. Renters in small apartments, who might seem to gain the most from not having to store large tools, borrowed less often. Some libraries have responded by opening branches closer to apartment neighborhoods, offering delivery by cargo bicycle, or stocking more items suited to small spaces, such as folding tables and food dehydrators.

The environmental case is similarly more complicated than it first appears. Sharing one drill instead of buying ten clearly reduces the materials and energy that go into manufacturing. But if borrowers drive across town to pick up and return each item, the emissions from those trips can cancel out part of the savings. Researchers who have tried to measure the net effect generally conclude that the benefit is real but depends heavily on how far people travel and how long the shared items last.

None of this has dampened the enthusiasm of the people who run these libraries, many of whom describe their work less as an economic experiment than as a way of rebuilding neighborhood ties. Volunteers teach classes on bicycle repair and knife sharpening; borrowers swap advice about which saw blade to use. A library of things, one organizer remarked, lends objects, but what it really circulates is know-how. That may be the hardest benefit to measure, and the one most likely to keep the shelves stocked.

1. The main purpose of the passage is to:
   • argue that libraries of things should replace hardware stores.
   • describe the growth of libraries of things and examine both the arguments for them and the complications they face.
   • explain how the first tool lending library in Berkeley was founded.
   • compare the costs of renting, borrowing, and buying household tools.
2. The author mentions the claim about a drill being used for thirteen minutes primarily to:
   • prove that most households own too many tools.
   • show that economists have carefully measured tool use.
   • illustrate a reasonable point while noting that the specific figure is doubtful.
   • criticize supporters of libraries of things for being dishonest.
3. As it is used in the passage, the term "idle capacity" refers to:
   • a resource that could be producing value but is sitting unused.
   • the number of items a library can store at one time.
   • the time a borrower must wait before an item is returned.
   • the cost of repairing tools that have been damaged.
4. According to the passage, a library of things lowers transaction costs mainly by:
   • charging lower fees than hardware stores.
   • teaching borrowers how to repair their own tools.
   • requiring borrowers to know their neighbors well.
   • making the exchange impersonal and predictable.
5. According to the passage, many organizers were surprised to find that their biggest problem was:
   • theft of valuable tools.
   • damage caused by careless borrowers.
   • demand for certain items that arrives all at once.
   • a lack of volunteers to run the library.
6. The example of the lawn aerators mainly illustrates that:
   • seasonal items are the most often stolen.
   • buying enough items to meet peak demand would recreate the problem of unused objects.
   • libraries should stop lending outdoor equipment.
   • most borrowers prefer to reserve items weeks in advance.
7. According to the study described in the passage, the most frequent users of lending libraries tended to be:
   • renters in small apartments.
   • homeowners with cars.
   • volunteers who teach repair classes.
   • people who live near library branches.
8. Which of the following statements best summarizes the author's view of the environmental benefits of libraries of things?
   • The benefits are real but depend on how far borrowers travel and how long items last.
   • The benefits are greatly exaggerated and probably do not exist.
   • The benefits are larger than the economic benefits.
   • The benefits have been measured precisely and are the same everywhere.
9. The organizer's remark that a library of things "really circulates" know-how suggests that the organizer believes the library's most important function is:
   • saving members money on tools.
   • reducing the amount of manufacturing.
   • keeping track of who borrows each item.
   • helping people share practical skills and knowledge.

Passage III

Humanities. Read the passage and choose the best answer to each question. Answer on the basis of what the passage states or implies.

HUMANITIES: This passage is adapted from an essay about the history of typefaces.

Most readers notice a typeface only when it fails them: when the letters on a medicine label are too small, or a road sign cannot be read at speed, or a wedding invitation is so ornate that the date disappears into the flourishes. When type is working well, it is invisible. Yet every letter on a printed page or a screen is the result of choices made by someone, often centuries ago, about how a shape should look and what it should do.

Consider italic type, which today serves mostly to add emphasis or to mark the title of a book. It began with a different purpose entirely. In 1501, the Venetian printer Aldus Manutius published an edition of the Roman poet Virgil in a small format that could be carried in one hand. To fit the text onto these compact pages, Aldus needed a narrow letter, and he commissioned one from the punchcutter Francesco Griffo. Griffo based his design on the slanted, flowing handwriting that scholars and officials of the time used for letters and documents. The new type saved space, and the small books sold well. Italic was not yet an accent within roman text; whole books were set in it.

Over the following century, printers gradually began pairing italic with the upright roman letters that had become standard for most text. Italic became a companion rather than a rival, and its role shifted from saving space to signaling difference: a foreign word, a quotation, a word the writer wanted the reader to hear with extra force. The shape stayed largely the same, but its meaning changed with its use.

Something similar happened, much later, with sans serif type: plain letters without the small finishing strokes, called serifs, that end the lines of most traditional typefaces. The first known sans serif type for printing appeared in a London type founder's specimen around 1816. It showed only capital letters, and it was met with little enthusiasm. Through much of the nineteenth century, sans serif faces were used mainly for posters and advertisements, where they could be made large and heavy enough to shout. Critics found them crude. One common name for them in England was "grotesque," and it was not entirely meant as a compliment.

The reputation of sans serif began to change in the early twentieth century, when designers came to value exactly the qualities critics had disliked. In 1916 the calligrapher Edward Johnston completed an alphabet for the London Underground, a clean sans serif meant to be read quickly by passengers moving through crowded stations. Johnston studied the proportions of ancient Roman inscriptions and brought their geometric clarity to letters stripped of ornament. The result was so successful that a version of it still guides travelers in London today. For a new generation of designers, plain letters no longer looked crude. They looked modern, honest, and efficient.

By the middle of the century, sans serif had become the voice of corporations, airports, and governments. Faces such as Helvetica, first released in Switzerland in 1957, were praised for their neutrality: they seemed to carry information without adding any opinion of their own. Critics later questioned whether any typeface could truly be neutral. A letter shape associated with banks and government forms, they argued, carries the authority of banks and government forms, whether or not its designer intended it to.

The arrival of screens added a new chapter. Early computer displays had so few dots per inch that the fine serifs of traditional book faces broke apart into jagged fragments, while sans serif faces, with their simpler strokes, held up better. For a time, designers repeated a rule that serif type was for print and sans serif type was for screens. As displays have grown sharper, that rule has weakened, and many reading apps now let readers choose for themselves.

What the history of type suggests is that a letter's meaning is not fixed in its shape. Italic was a space-saving device before it was a way of raising one's voice; sans serif was vulgar before it was modern, and modern before it was corporate. The shapes change slowly, but the associations readers bring to them change faster. A designer choosing a typeface today is therefore choosing not only a set of shapes but a set of histories, some of which the reader may feel without ever being able to name.

1. Which of the following statements best expresses the main idea of the passage?
   • Sans serif type is easier to read than serif type in every situation.
   • Italic type was invented to make books more beautiful.
   • The meanings readers associate with typefaces have changed over time as the typefaces were used in new ways.
   • Modern typefaces are better designed than older ones.
2. According to the passage, Aldus Manutius needed a narrow letter in order to:
   • fit text onto small books that could be carried in one hand.
   • imitate the handwriting of the poet Virgil.
   • add emphasis to important words in his books.
   • compete with printers in London.
3. According to the passage, Griffo based his italic design on:
   • ancient Roman inscriptions.
   • the handwriting that scholars and officials used for letters and documents.
   • the capital letters used on posters.
   • the upright roman letters used in most books.
4. The statement that italic "became a companion rather than a rival" most nearly means that italic came to be:
   • used in place of roman type in most books.
   • abandoned by printers in favor of roman type.
   • redesigned so that it looked like roman type.
   • used together with roman type to set certain words apart.
5. The author mentions that sans serif faces were called "grotesque" in England mainly to:
   • show how poorly early sans serif type was regarded.
   • explain where the first sans serif type was made.
   • suggest that sans serif type was used for horror stories.
   • prove that critics preferred italic type.
6. According to the passage, Edward Johnston's alphabet for the London Underground drew on:
   • the proportions of ancient Roman inscriptions.
   • the italic type designed by Griffo.
   • the heavy letters used on nineteenth century posters.
   • the dot patterns of early computer screens.
7. The critics described in the sixth paragraph would most likely agree with which of the following statements?
   • Helvetica is the most neutral typeface ever designed.
   • A typeface's designer fully controls how readers will react to it.
   • Typefaces should never be used by banks or governments.
   • A typeface can take on associations from the places where it is often used.
8. According to the passage, sans serif faces were favored on early computer screens because:
   • they took up less space than serif faces.
   • their simpler strokes displayed more clearly on low-resolution screens.
   • readers had come to see them as modern and honest.
   • screen designers were trained mainly in poster design.
9. Based on the passage, which of the following events happened first?
   • Edward Johnston completed his alphabet for the London Underground.
   • Helvetica was first released.
   • Printers began pairing italic with upright roman letters.
   • The first known sans serif type appeared in a London specimen.

Passage IV

Natural Science. Read the passage and choose the best answer to each question. Answer on the basis of what the passage states or implies.

NATURAL SCIENCE: This passage is adapted from an article about glaciers that suddenly speed up.

Most glaciers move so slowly that a person watching one would see nothing happen at all. A typical valley glacier might advance a few dozen to a few hundred meters in a year, creeping downhill under its own weight. But a small fraction of the world's glaciers behave differently. For years or decades they move slowly, or even seem to stall, and then, over a period of months, they race forward at ten to a hundred times their usual speed, their surfaces breaking into a maze of crevasses. Glaciologists call these events surges, and the glaciers that experience them surge-type glaciers.

Surge-type glaciers are rare: by most estimates they make up only about one percent of the glaciers on Earth. They are also unevenly distributed. They cluster in a few regions, including Alaska and the Yukon, the Svalbard archipelago north of Norway, parts of the Karakoram range in Asia, and Iceland, while large glaciated regions elsewhere contain almost none. This clustering has long suggested to scientists that surges depend on some combination of climate, bedrock, and glacier shape that occurs only in particular places.

A surge cycle has two phases. During the long quiescent phase, the glacier moves too slowly to carry away all the snow that accumulates in its upper basin. Ice builds up high on the glacier while the lower part thins and may even retreat. The glacier's surface grows steeper. Eventually, during the short active phase, the stored ice is released all at once and moves rapidly downhill, thickening the lower glacier and sometimes pushing its front kilometers beyond its earlier position. Then the glacier slows, and the cycle begins again.

What actually triggers a surge has been a central question in glaciology for more than half a century. The most detailed early answer came from Variegated Glacier in Alaska, which surged in 1982 and 1983 while a team of researchers watched. They drilled boreholes through the ice and measured the water pressure at the glacier's bed. Before the surge, meltwater drained from the bed through a network of tunnels, which carried it away efficiently. As the surge began, the researchers found, this tunnel network gave way to a system of many small, linked cavities that drained water poorly. Water pressure at the bed rose until it nearly equaled the weight of the overlying ice, which lifted the glacier slightly off its bed and allowed it to slide. When the efficient tunnels re-formed, a sudden flood of muddy water burst from the glacier's front, and the surge stopped within days.

This "hydrologic switch" explained Variegated Glacier well, but it did not fit every surge. Many surging glaciers in Svalbard, for example, speed up gradually over several years rather than suddenly, and slow down gradually too. Researchers there proposed a "thermal switch." In these glaciers, much of the bed is frozen to the ground during the quiescent phase. As ice thickens in the upper basin, it insulates the bed and traps heat from the Earth below and from friction, until the bed reaches the melting point. Once the bed thaws, water appears, the ice begins to slide, and the surge spreads.

More recently, some glaciologists have argued that the two explanations are not really competitors. In a framework based on the glacier's energy budget, both are seen as ways that a glacier gains heat or meltwater faster than it can get rid of them. A glacier that cannot balance this budget through steady, slow motion is forced into cycles of storage and release. The framework also offers an account of why surges cluster where they do: the regions with many surge-type glaciers tend to have climates that are neither so cold and dry that little meltwater forms nor so warm and wet that the glacier can drain meltwater efficiently all year.

The question is more than academic. Surging glaciers can block rivers and create lakes that later burst, flooding valleys downstream. In the Karakoram, where roads and villages lie below glaciers, predicting a surge can matter for people's safety. Glaciologists now use satellites to track the surface speed of thousands of glaciers, watching for the slow thickening and steepening that signal the end of a quiescent phase. They still cannot say exactly when a particular glacier will surge, but they are increasingly able to say which ones are getting ready.

1. The main purpose of the passage is to:
   • argue that glacier surges are caused by climate change.
   • explain what glacier surges are and describe how scientists' explanations of their causes have developed.
   • describe the history of glacier research in Alaska.
   • compare the dangers of glacier surges in different countries.
2. According to the passage, surge-type glaciers make up approximately what portion of the glaciers on Earth?
   • One percent
   • Ten percent
   • One quarter
   • One half
3. Which of the following happens during the quiescent phase of a surge cycle, according to the passage?
   • The glacier's front advances several kilometers.
   • Meltwater floods out from the glacier's front.
   • Ice builds up in the upper basin while the lower glacier thins.
   • The glacier's surface becomes flatter.
4. According to the passage, the researchers at Variegated Glacier found that the surge began when:
   • the bed of the glacier froze to the ground.
   • an efficient tunnel network was replaced by poorly draining linked cavities.
   • heavy snowfall added weight to the lower glacier.
   • the researchers' boreholes allowed water to escape.
5. The passage suggests that the flood of muddy water at the end of the Variegated Glacier surge occurred because:
   • the glacier's bed suddenly thawed.
   • a lake formed by the glacier burst through a dam of ice.
   • efficient drainage tunnels formed again and released stored water.
   • the glacier's surface began to melt rapidly in summer.
6. Based on the passage, the main difference between the hydrologic switch and the thermal switch is that the thermal switch:
   • depends on the thawing of a glacier bed that was frozen to the ground.
   • applies only to glaciers in Alaska.
   • involves no meltwater at all.
   • explains why surges stop suddenly within days.
7. The author mentions surging glaciers in Svalbard mainly to provide an example of glaciers that:
   • surge more often than any other glaciers.
   • do not fit the hydrologic switch explanation well.
   • were the first surge-type glaciers to be studied.
   • pose the greatest danger to nearby villages.
8. According to the energy budget framework, regions with many surge-type glaciers tend to have climates that are:
   • extremely cold and dry.
   • extremely warm and wet.
   • warm and dry.
   • neither extremely cold and dry nor extremely warm and wet.
9. As it is used in the last paragraph, the word "academic" most nearly means:
   • related to a university degree.
   • of only theoretical interest.
   • carefully researched.
   • difficult to understand.

Science (40 phút)

Passage I

Read the passage, study the figure if there is one, and choose the best answer to each question.

Honeybee colonies kept in cities forage on street trees, gardens, and weedy lots. Researchers placed 4 hives at each of 5 urban sites (A through E) for one season. For each site they measured the percent of land within 1 km covered by impervious surfaces (pavement and roofs) and counted the number of flowering plant species within 1 km.

Every two weeks, pollen was collected from the hive entrances and examined under a microscope. The researchers recorded the total number of different pollen types found at each site over the season. At the end of the season, they weighed the honey produced. Table 1 shows the results (honey yield is the mean for the 4 hives at each site).

1. According to Table 1, which site had the greatest mean honey yield?
   • Site A
   • Site B
   • Site C
   • Site E
2. Based on Table 1, as the number of flowering species within 1 km increased, honey yield:
   • increased only.
   • decreased only.
   • increased and then decreased.
   • stayed about the same.
3. Based on Table 1, as impervious surface decreased from 85% to 20%, honey yield:
   • increased only.
   • decreased only.
   • decreased and then increased.
   • increased and then decreased.
4. Suppose a sixth site had 70 flowering species within 1 km. Based on the relationship between flowering species and honey yield in Table 1, the mean honey yield at that site would most likely be:
   • less than 15 kg per hive.
   • between 18 and 24 kg per hive.
   • between 26 and 29 kg per hive.
   • greater than 32 kg per hive.
5. How many more pollen types were found at Site C than at Site E?
   • 20
   • 24
   • 34
   • 48
6. A student hypothesized that hives at sites with more flowering species nearby collect more types of pollen. Do the data in Table 1 support this hypothesis?
   • No, because Site A had the most pollen types but not the most flowering species.
   • Yes, because the number of pollen types increased as the number of flowering species increased.
   • Yes, because the site with the most impervious surface had the most pollen types.
   • No, because the number of pollen types was the same at every site.

Passage II

Read the passage, study the figure if there is one, and choose the best answer to each question.

Soil in some coastal rice-growing regions, such as parts of the Mekong Delta, becomes salty when seawater moves inland during the dry season. Scientists studied how salinity affects the germination (sprouting) of rice seeds.

Experiment 1: For each of 2 rice varieties, V1 and V2, 5 dishes of 100 seeds each were prepared. Each dish was watered with a sodium chloride (NaCl) solution of a different concentration: 0, 50, 100, 150, or 200 millimolar (mM). All dishes were kept at 30°C. After 7 days, the percent of seeds that had germinated in each dish was recorded (see Figure 1).

Experiment 2: Four dishes of 100 V2 seeds were each watered with 100 mM NaCl solution and kept at 20°C, 25°C, 30°C, or 35°C. After 7 days, the percent of seeds that had germinated was recorded, along with the mean germination time (the average number of days a germinated seed took to sprout). Results: at 20°C, 52% germinated, with a mean germination time of 5.8 days; at 25°C, 74% germinated, with a mean germination time of 4.1 days; at 30°C, 88% germinated, with a mean germination time of 3.2 days; at 35°C, 80% germinated, with a mean germination time of 3.6 days.

1. In Experiment 1, as NaCl concentration increased, the percent germination of V1:
   • increased only.
   • decreased only.
   • increased and then decreased.
   • decreased and then increased.
2. In Experiment 1, at which NaCl concentration was the difference between the percent germination of V2 and that of V1 greatest?
   • 50 mM
   • 100 mM
   • 150 mM
   • 200 mM
3. Based on Experiment 1, which variety is more tolerant of salt during germination?
   • V1, because its germination was higher at 0 mM.
   • V2, because its germination decreased less as NaCl concentration increased.
   • V1, because its germination decreased more as NaCl concentration increased.
   • V2, because its germination was lower at 0 mM.
4. In Experiment 2, which of the following was held constant?
   • Temperature
   • NaCl concentration
   • Percent germination
   • Mean germination time
5. In Experiment 2, at which temperature did V2 seeds show both the highest percent germination and the shortest mean germination time?
   • 20°C
   • 25°C
   • 30°C
   • 35°C
6. If V1 seeds had been tested in Experiment 1 with a 125 mM NaCl solution, the percent germination would most likely have been:
   • greater than 90%.
   • between 71% and 88%.
   • between 42% and 71%.
   • less than 18%.
7. A student claimed that, at 100 mM NaCl, V2 seeds germinated both more completely and more quickly at 35°C than at 25°C. Do the results of Experiment 2 support this claim?
   • No, because germination was lower at 35°C than at 25°C.
   • No, because the mean germination time was longer at 35°C than at 25°C.
   • No, because neither germination nor germination time differed.
   • Yes, because germination was higher and the mean germination time was shorter at 35°C.

Passage III

Read the passage, study the figure if there is one, and choose the best answer to each question.

In summer, the discharge (volume of water flowing past a point per second) of a stream draining a glacier rises and falls each day as the glacier's surface melts. Hydrologists measured the discharge of one glacial stream every 3 hours over a single day in July and a single day in September. Hour 0 is midnight, and hour 24 is the following midnight. Figure 1 shows the results.

On both days, the air temperature at the glacier's surface was highest at about hour 14 (2:00 p.m.) and lowest at about hour 5.

1. According to Figure 1, at which hour shown was the July discharge greatest?
   • Hour 9
   • Hour 12
   • Hour 15
   • Hour 18
2. Based on Figure 1 and the passage, the greatest July discharge shown occurred about how many hours after the air temperature was highest?
   • 1 hour
   • 4 hours
   • 8 hours
   • 13 hours
3. What was the difference between the greatest and the least July discharges shown in Figure 1?
   • 2.2 m³/s
   • 6.0 m³/s
   • 8.2 m³/s
   • 11.0 m³/s
4. Which of the following statements about Figure 1 is true?
   • The September discharge was greater than the July discharge at hour 0.
   • The July and September discharges were equal at hour 12.
   • The September discharge was greatest at hour 12.
   • The September discharge was less than the July discharge at every hour shown.
5. At hour 18, the July discharge was approximately how many times the September discharge?
   • 1.5
   • 3
   • 6
   • 11
6. Based on Figure 1, the July discharge at hour 16 was most likely:
   • less than 6.0 m³/s.
   • between 6.0 and 9.5 m³/s.
   • between 9.5 and 11.0 m³/s.
   • greater than 11.0 m³/s.

Passage IV

Read the passage, study the figure if there is one, and choose the best answer to each question.

When a small sphere falls through a thick liquid, it speeds up briefly and then falls at a constant speed called its terminal speed. Students studied how terminal speed depends on the sphere and on the liquid.

A tall clear tube was filled with glycerin (density 1.26 g/cm³). Marks were placed 20 cm apart near the middle of the tube, where each sphere had already reached its terminal speed. For each trial, a sphere was released at the top, and the time it took to pass between the marks was used to calculate terminal speed.

Experiment 1: Steel spheres with diameters of 2 mm, 4 mm, and 6 mm were dropped in glycerin at 20°C (Trials 1 to 3).

Experiment 2: A 4 mm steel sphere was dropped in glycerin heated or cooled to 10°C, 30°C, and 40°C (Trials 4 to 6). Trial 2 provided the result at 20°C.

Experiment 3: 4 mm spheres made of glass (density 2.5 g/cm³), aluminum (2.7 g/cm³), and lead (11.3 g/cm³) were dropped in glycerin at 20°C (Trials 7 to 9). The density of steel is 7.8 g/cm³, and Trial 2 provided the result for steel.

1. In Experiment 1, as the diameter of the steel sphere increased, the terminal speed:
   • increased only.
   • decreased only.
   • increased and then decreased.
   • remained the same.
2. When the diameter of the steel sphere was tripled from 2 mm to 6 mm, the terminal speed increased by a factor of about:
   • 3
   • 6
   • 9
   • 12
3. Based on Trials 2, 4, 5, and 6, as the temperature of the glycerin increased, the terminal speed of the 4 mm steel sphere:
   • increased only.
   • decreased only.
   • decreased and then increased.
   • remained the same.
4. Which trials should be compared to determine how sphere material affects terminal speed?
   • Trials 1, 2, and 3
   • Trials 2, 4, 5, and 6
   • Trials 2, 7, 8, and 9
   • Trials 3, 6, and 9
5. Based on Experiment 3 and the densities given, which of the following statements is best supported?
   • Terminal speed increased as the density of the sphere increased.
   • Terminal speed decreased as the density of the sphere increased.
   • Terminal speed did not depend on the density of the sphere.
   • Glass spheres fell faster than lead spheres.
6. If a 4 mm steel sphere were dropped in glycerin at 25°C, its terminal speed would most likely be:
   • less than 1.4 cm/s.
   • between 1.4 and 4.0 cm/s.
   • between 4.0 and 9.2 cm/s.
   • greater than 20.1 cm/s.
7. In Trial 2, about how long did the sphere take to travel the 20 cm between the marks?
   • 0.2 s
   • 0.8 s
   • 2 s
   • 5 s

Passage V

This passage presents two viewpoints. Read it and choose the best answer to each question.

Fairy circles are round patches of bare sand, 2 to 12 m across, each surrounded by a ring of grass that is taller than the grass between circles. They occur by the millions in a narrow band of dry grassland along the eastern edge of the Namib Desert, where yearly rainfall is about 50 to 150 mm. The circles are spaced in a strikingly regular pattern, and an individual circle can last for several decades. Two scientists explain how the circles form.

Scientist 1

Fairy circles are made by sand termites that live underground. The termites eat the roots of grasses, and the grass inside a circle dies. Because no plants grow on the bare patch, rainwater that soaks into it is not taken up by roots and is not lost to the air through leaves. The water is stored in the sand below, where it keeps the termite colony alive during dry months and feeds the tall grass at the edge of the circle. Termites are found in the soil of most circles that have been dug up. After rains, soil moisture 30 to 100 cm below the surface is higher inside circles than in the grassland between them. Neighboring termite colonies compete for food, and this competition keeps the colonies, and therefore the circles, evenly spaced.

Scientist 2

Fairy circles form because grasses compete for scarce water. Where rain is very limited, there is not enough water to support a continuous cover of grass. The grasses at the edge of a bare patch spread their roots outward and draw water from the sand beneath it, so that new seedlings inside the patch dry out and die. In this way, the grass organizes itself into a pattern of bare patches separated by grass, and competition for water spaces the patches evenly. After rains, grass seedlings that sprout inside circles die within weeks, even in circles where no termite damage is found on their roots. Similar evenly spaced bare patches occur in dry grasslands of Western Australia, where termites are not consistently present in the patches. Circles occur only within a limited range of rainfall: where it is wetter, grass covers the ground completely.

1. Both scientists would most likely agree that:
   • water availability plays a role in the formation or maintenance of fairy circles.
   • termites are the main cause of fairy circles.
   • the grass at the edge of a circle is shorter than the grass between circles.
   • fairy circles occur only in Australia.
2. According to Scientist 1, the grass inside a fairy circle dies because:
   • termites eat the roots of the grass.
   • grass at the edge takes all the water from the sand.
   • the soil inside the circle is too salty.
   • rainwater runs off the bare sand.
3. Which of the following findings, if true, would most strengthen Scientist 2's viewpoint?
   • Termites are found in the soil of every fairy circle that is dug up.
   • Soil moisture deep under circles is higher than between circles after rains.
   • Fairy circles are found in regions with yearly rainfall of more than 500 mm.
   • Fairy circles form in plots from which all termites have been removed by barriers.
4. Which of the following observations would most weaken Scientist 1's viewpoint?
   • Many newly formed fairy circles contain no termites at all.
   • Termite colonies compete with one another for food.
   • The grass at the edge of circles is taller than other grass.
   • Fairy circles can last for several decades.
5. Scientist 2 most likely mentions the bare patches in Western Australia in order to suggest that:
   • termites in Australia are larger than termites in the Namib.
   • evenly spaced bare patches can form where termites are not consistently present.
   • fairy circles last longer in Australia than in the Namib.
   • Australian grasses need more water than Namib grasses.
6. Based on Scientist 1's viewpoint, a few days after a heavy rain, the moisture of the sand 50 cm below the surface should be:
   • lower inside a circle than in the grassland between circles.
   • the same inside and outside a circle.
   • higher inside a circle than in the grassland between circles.
   • zero both inside and outside a circle.
7. Suppose that over several decades, the yearly rainfall in part of the fairy circle region rose to about 400 mm. Based on Scientist 2's viewpoint, the fairy circles in that area would most likely:
   • become larger and more evenly spaced.
   • be filled in by grass and disappear.
   • be taken over by termite colonies.
   • remain exactly as they were.

Passage VI

Read the passage, study the figure if there is one, and choose the best answer to each question.

The amount of oxygen gas that can dissolve in water (its solubility) depends on the water's temperature and salinity (the concentration of dissolved salts, in parts per thousand, ppt). Freshwater has a salinity of about 0 ppt, and seawater about 35 ppt. Water in which the dissolved oxygen equals the solubility is said to be 100% saturated.

Figure 1 shows the solubility of oxygen, in milligrams per liter (mg/L), in water at 3 salinities and 5 temperatures, for water in contact with air at sea level.

1. According to Figure 1, what is the solubility of oxygen in freshwater (0 ppt) at 20°C?
   • 9.1 mg/L
   • 11.3 mg/L
   • 12.8 mg/L
   • 14.6 mg/L
2. Based on Figure 1, as water temperature increases, the solubility of oxygen:
   • increases at every salinity.
   • decreases at every salinity.
   • increases in freshwater but decreases in seawater.
   • does not change.
3. Based on Figure 1, at a given temperature, how does the solubility of oxygen change as salinity increases from 0 ppt to 35 ppt?
   • It increases.
   • It decreases.
   • It first increases and then decreases.
   • It stays the same.
4. Based on Figure 1, the solubility of oxygen in seawater (35 ppt) at 25°C is closest to:
   • 5.3 mg/L
   • 6.8 mg/L
   • 8.2 mg/L
   • 9.1 mg/L
5. For freshwater, by how much does the solubility of oxygen decrease from 0°C to 40°C?
   • 3.3 mg/L
   • 5.9 mg/L
   • 7.0 mg/L
   • 8.2 mg/L
6. A sample of seawater (35 ppt) at 30°C contains 3.1 mg/L of dissolved oxygen. About what percent saturated is the sample?
   • 25%
   • 50%
   • 75%
   • 100%
7. A shrimp farmer in a coastal pond with a salinity of 17.5 ppt measured 9.5 mg/L of dissolved oxygen at 2:00 p.m., when the water temperature was 32°C. Compared with the solubility shown in Figure 1 for these conditions, the measured value was:
   • lower, because the solubility at 32°C and 17.5 ppt is greater than 10 mg/L.
   • about equal, because the solubility at 32°C and 17.5 ppt is about 9.5 mg/L.
   • higher, because the solubility at 32°C and 17.5 ppt is less than 6.9 mg/L.
   • higher, because the solubility at 32°C and 17.5 ppt is greater than 12 mg/L.