1、托福-51 及答案解析(总分：119.98，做题时间：90 分钟)一、READING(总题数：0，分数：0.00)二、Set 1(总题数：1，分数：13.00)MASS WASTING PROCESSES1 The downslope movement of rock, mud, or other material under the influence of gravity is known as mass wasting. While the angle of the slope is a major factor in the potential for mass wasting, th
2、e slope is not the sole determiner of mass wasting events. Water plays a significant role, especially where it is plentiful during the rainy season. Earthquakes may cause rockslides, mudflows, and other mass movements. Factors such as the presence or absence of vegetation and human activities can al
3、so influence the potential for mass wasting. 2 One way to classify mass wasting processes is on the basis of the material involved, such as rock, debris, earth, or mud. The manner in which the material moves is also important and is generally described as a fall, a slide, or a flow. A fall occurs wh
4、en weathering loosens boulders from cliffs or rock faces, causing the boulders to break away and fall. A slide takes place whenever material remains fairly coherent and moves along a well-defined surface. A flow involves the movement of debris containing a large amount of water. 3 Many mass wasting
5、processes are described as slides. Rockslides occur when a coherent mass of rock breaks loose and slides down a slope as a unit. If the material involved is mostly separate pieces, it is called a debris slide. Slides are among the fastest and most destructive mass movements. Usually rockslides occur
6、 in a geologic setting where the rock layers are inclined, or where there are joints and fractures in the rock that are parallel to the slope. When such a rock unit is undercut at the base of the slope, it loses support and the rock eventually collapses. Rain or snowmelt can trigger a rockslide by w
7、etting the underlying surface to the point that friction can no longer hold the rock in place. The fastest type of slide is a rock avalanche, in which a mass of rock literally floats on air as it moves downslope. The high speed of a rock avalanche is the result of air becoming trapped and compressed
8、 beneath the falling mass of debris, allowing it to move down the slope as a buoyant sheet. 4 Mudflows are relatively rapid mass wasting events that involve soil and a large amount of water. Because of their fluid properties, mudflows follow canyons and stream channels. Mudflows often take place in
9、semiarid mountainous regions and on the slopes of some volcanoes. Although rainstorms in semiarid regions are infrequent, they are typically heavy when they occur. When a rainstorm or rapidly melting snow creates a sudden flood, large quantities of soil and loose rock are washed into nearby stream c
10、hannels because there is usually little or no vegetation to anchor the surface material. The result is a flowing mass of well-mixed mud, soil, rock, and water. The consistency of the mudflow may be similar to that of wet concrete, or it may be a soupy mixture not much thicker than muddy water. The w
11、ater content influences the rate of flow across the surface. When a mudflow is dense, it moves more slowly, but it can easily carry or push large boulders, trees, and even houses along with it. 5 In dry mountainous areas such as southern California, mudflows are a serious hazard to development on an
12、d near canyon hillsides. The removal of native vegetation by brush fires has increased the probability of these destructive events. Past mudflows have contributed to the buildup of fan-shaped deposits at canyon mouths. Such fans are relatively easy to build on and often have scenic views, so many ha
13、ve become desirable sites for residential development. However, because mudflows occur infrequently, homeowners are often unaware of the potential danger of building on the site of a previous mudflow. 6 Highly fluid, fast-flowing mudflows incorporate fine-grained sediment and are common after volcan
14、ic eruptions that produce large volumes of volcanic ash. Mudflows containing volcanic debris are called lahars, a word originating in Indonesia, a region that experiences many volcanic eruptions. Lahars occur when highly unstable layers of ash and debris become saturated with water and flow down ste
15、ep volcanic slopes along stream channels. In the northwestern United States, the eruption of Mount St. Helens in 1980 created several lahars that raced down the valley of the Toutle River, altering the landscape in a relatively short period.（分数：13.00）(1).All of the following are given as factors in
16、mass wasting EXCEPT（分数：1.00）A.the angle of the slopeB.the presence of waterC.the absence of plantsD.the type of mineral(2).The name of a mass wasting process is a reflection of（分数：1.00）A.the area in which the movement occursB.the material that is moved and the way it movesC.the rate of movement rela
17、tive to other processesD.the mass and volume of the material involved(3).The word trigger in paragraph 3 is closest in meaning to（分数：1.00）A.preventB.imitateC.causeD.decrease(4).Why does a rock avalanche move faster than other types of rockslides?（分数：1.00）A.The rock moves over a layer of compressed a
18、ir.B.The rainfall is heavy where avalanches occur.C.The rock breaks apart as it moves downslope.D.The angle of the slope is almost vertical.(5).The word buoyant in paragraph 3 is closest in meaning to（分数：1.00）A.floatingB.dangerousC.heavyD.sticky(6).The word anchor in paragraph 4 is closest in meanin
19、g to（分数：1.00）A.pushB.replaceC.holdD.improve(7).In what significant way do flows differ from other mass wasting processes?（分数：1.00）A.Flows do not occur in dry regions.B.Flows consistently move at a high speed.C.Flows contain greater percentages of rock.D.Flows have higher water content.(8).Which sent
20、ence below best expresses the essential information in the highlighted sentence in paragraph 5? Incorrect choices change the meaning in important ways or leave out essential information.（分数：1.00）A.Fire has destroyed much of the original vegetation, so mudflows are now more likely.B.More damage to ve
21、getation is caused by brush fires than by any other natural event.C.It is necessary to remove dead and damaged vegetation after a mudflow but not after a fire.D.Fires occur frequently in areas where the vegetation has been cleared for development.(9).What can be inferred from paragraph 5 about mudfl
22、ows in some parts of southern California?（分数：1.00）A.Mudflows rarely occur more than once in the same location.B.Mudflows cause the worst damage in areas that are heavily forested.C.Mudflows occur more often than other natural disasters such as fires.D.Mudflows are so dangerous because people do not
23、expect them to occur.(10).It can be inferred from paragraph 6 that lahars（分数：1.00）A.contain less water than other mudflowsB.occur in IndonesiaC.are relatively harmless eventsD.cause volcanic eruptions(11).Why does the author use the word raced in paragraph 6 while describing the lahars caused by the
24、 eruption of Mount St. Helens?（分数：1.00）A.To show that lahars are faster than rock avalanchesB.To state ironically that lahars do not actually move quicklyC.To emphasize the fast speed of laharsD.To explain why people could not outrun the mudflows(12).Look at the four squares, A, B, C, and D, which i
25、ndicate where the following sentence could be added to the passage. Where would the sentence best fit? Thus, rockslides occur more frequently during the spring, when heavy rains and melting snow are most prevalent. Many mass wasting processes are described as slides. Rockslides occur when a coherent
26、 mass of rock breaks loose and slides down a slope as a unit. A If the material involved is largely unconsolidated, it is called a debris slide. Slides are among the fastest and most destructive mass movements. Usually rockslides occur in a geologic setting where the rock layers are inclined, or whe
27、re there are joints and fractures in the rock that are parallel to the slope. B When such a rock unit is undercut at the base of the slope, it loses support and the rock eventually collapses. Rain or snowmelt can trigger a rockslide by wetting the underlying surface to the point that friction can no
28、 longer hold the rock in place. C The fastest type of slide is a rock avalanche, in which a mass of rock literally floats on air as it moves downslope. The high speed of a rock avalanche is the result of air becoming trapped and compressed beneath the falling mass of debris, allowing it to move down
29、 the slope as a buoyant sheet. D（分数：1.00）(13).Select the appropriate phrases from the answer choices and match them to the type of mass wasting to which they refer. TWO of the answer choices will NOT be used. This question is worth 4 points. Rockslides Mudflows Answer ChoicesA. Occur when a mass of
30、rock moves downslope as a unit B. Involve the mass movement of soil containing a large amount of water C. May have the consistency of wet concrete or soup D. Occur where sloping rock layers have cracks parallel to the slope E. Occur when a layer of snow breaks loose and moves rapidly downslope F. In
31、clude the transportation of organic materials by wind and water G. Float on a thin layer of air as they move rapidly down a mountain H. Move slowly but with enough force to carry away trees and houses I. Occur on slopes where layers of volcanic debris become extremely wet（分数：1.00）三、Set 2(总题数：1，分数：13
32、.00)THE TRIANGLE FACTORY FIRE1 The fire at the Triangle Waist Company in New York City was one of the worst workplace disasters in the history of labor. The incident highlighted the inhumane working conditions faced by many industrial workers, including low wages, excessively long hours, and an unsa
33、nitary and dangerous work environment. The Triangle Waist Company, a shirt factory, was a typical sweatshop in the heart of New York“s garment district. Most of the workers were women, some as young as 15 years old, mostly recent Italian and European Jewish immigrants who had come to the United Stat
34、es with their families to seek a better life. Already struggling with a new language and culture, these workers could not speak out about working conditions for fear of losing their desperately needed jobs, and this forced them to endure exploitation by the factory owners. 2 On March 25, 1911, one o
35、f the five hundred employees of the Triangle Waist factory noticed that a rag bin near her eighth-floor workstation was on fire. She and her co-workers immediately tried to extinguish the flames, but their efforts proved futile, and piles of fabric ignited all over the eighth floor. The factory mana
36、ger ordered his employees to unroll the fire extinguisher hose, but they found it rotted and useless. Panic erupted as the fire spread. 3 The shirt factory occupied the top three floors of the ten-story Asch Building. The seventy employees who worked on the tenth floor escaped the fire by way of the
37、 staircases or by climbing onto the roof, where students from New York University, located across the street, stretched ladders over to the Asch Building. The 260 workers on the ninth floor had the worst luck of all. Although the eighth-floor workers tried to warn them by telephone, the call did not
38、 reach them, and by the time the ninth-floor workers learned about the fire, their routes of escape were mostly blocked. When they found many of the exit doors locked, some managed to climb down the cables of the freight elevator. Others crammed into one narrow stairway. Still others climbed onto th
39、e single, inadequately constructed fire escape. However, the fire escape led nowhere, and it bent under the weight of hundreds of workers trying to escape. The spindly structure separated from the wall, falling to the ground and carrying many people with it. 4 To combat the disaster, the New York Fi
40、re Department sent thirty-five pieces of equipment, including a hook and ladder. The young women trapped on the ninth floor waited on the window ledges to be rescued, only to discover that the ladder, fully raised, stopped far below them at the sixth floor. Water from the hoses could not reach the t
41、op floors, and many workers chose to jump to their deaths rather than to burn alive. Within minutes, the factory was consumed by flame, killing 146 workers, mostly immigrant women. City officials set up a temporary morgue in a building on 26th Street, and over the next few days streams of survivors
42、filed through the building to identify the dead. 5 The ten-story Asch Building was a firetrap typical of the working conditions of the period, and the Triangle fire tragically illustrated that fire inspections and safety precautions were very inadequate. The victims of the fire were trapped by the l
43、ack of fire escapes and by management“s practice of locking the exit doors during work hours. The incident had a profound impact on women“s unionism and job safety, affecting local and national politics in the process. An era of progressive reform began to sweep the nation, as people decided that go
44、vernment had a responsibility to ensure that private industry protected the welfare of workers. There was a public outcry for laws to regulate workplace safety. The New York Factory Investigating Commission was formed to examine the conditions in factories throughout the state, and their report led
45、to many new regulations in the years following the fire. 6 The fire at the Triangle Waist Company highlighted the excesses of industrialism. The tragedy remains in the collective memory of the labor movement, and the victims of the tragedy are still honored as martyrs at the hands of industrial gree
46、d.（分数：13.00）(1).All of the following characterized the factory of the Triangle Waist Company EXCEPT（分数：1.00）A.unsafe working conditionsB.a large number of female workersC.a strong labor unionD.workrooms on three floors(2).Which sentence below best expresses the essential information in the highlight
47、ed sentence in paragraph 1? Incorrect choices change the meaning in important ways or leave out essential information.（分数：1.00）A.Because they did not speak the same language as the factory owners, the workers were not able to discuss conditions in the factory.B.Language and culture were serious prob
48、lems in the workplace, but workers were even more afraid of being exploited by the factory owners.C.The factory owners forced the workers to learn a new language and culture because it was necessary for them to succeed in their jobs.D.The workers experienced cultural difficulties, poor conditions, a
49、nd exploitation without complaint because they needed their jobs.(3).The word ignited in paragraph 2 is closest in meaning to（分数：1.00）A.disappearedB.caught fireC.explodedD.were thrown out(4).Why does the author mention the fire extinguisher hose in paragraph 2?（分数：1.00）A.To emphasize the unsafe working conditionsB.To show the manager“s leadership skillsC.To illustrate the factory“s modern technologyD.To explain how the fire was eventually put out(5).According to the passage, how did many workers on the top floor manage to escape the fire?（分数：1.00）A.On the fire escapeB.On the elev
