1、托福（阅读）模拟试卷 6及答案与解析 一、 Sections Three： Reading Comprehension 0 “Migration from Asia“ The Asian migration hypothesis is today supported by most of the scientific evidence. The first “hard“ data linking American Indians with Asians appeared in the 1980s with the finding that Indians and northeast Asian
2、s share a common and distinctive pattern in the arrangement of the teeth. But perhaps the most compelling support for the hypothesis comes from genetic research. Studies comparing the DNA variation of populations around the world consistently demonstrate the close genetic relationship of the two pop
3、ulations, and recently geneticists studying a virus sequestered in the kidneys of all humans found that the strain of virus carried by Navajos and Japanese is nearly identical, while that carried by Europeans and Africans is quite different. The migration could have begun over a land bridge connecti
4、ng the continents. During the last Ice Age 70,000 to 10,000 years ago, huge glaciers locked up massive volumes of water and sea levels were as much as 300 feet lower than today. Asia and North America were joined by a huge subcontinent of ice-free, treeless grassland, 750 miles wide. Geologists have
5、 named this area Beringia, from the Bering Straits. Summers there were warm, winters were cold, dry and almost snow-free. This was a perfect environment for large mammals mammoth and mastodon, bison, horse, reindeer, camel, and saiga (a goatlike antelope). Small bands of Stone Age hunter-gatherers w
6、ere attracted by these animal populations, which provided them not only with food but with hides for clothing and shelter, dung for fuel, and bones for tools and weapons. Accompanied by a husky-like species of dog, hunting bands gradually moved as far east as the Yukon River basin of northern Canada
7、, where field excavations have uncovered the fossilized jawbones of several dogs and bone tools estimated to be about 27,000 years old. Other evidence suggests that the migration from Asia began about 30,000 years agoaround the same time that Japan and Scandinavia were being settled. This evidence i
8、s based on blood type. The vast majority of modern Native Americans have type O blood and a few have type A, but almost none have type B. Because modern Asian populations include all three blood types, however, the migrations must have begun before the evolution of type B, which geneticists believe
9、occurred about 30,000 years ago. By 25,000 years ago human communities were established in western Beringia, which is present-day Alaska. A But access to the south was blocked by a huge glacial sheet covering much of what is today Canada. How did the hunters get over those 2,000 miles of deep ice? T
10、he argument is that the climate began to warm with the passing of the Ice Age, and about 13,000 b.c.e. glacial melting created an ice-free corridor along the eastern front range of the Rocky Mountains. B Soon hunters of big game had reached the Great Plains. In the past several years, however, new a
11、rchaeological finds along the Pacific coast of North and South America have thrown this theory into question. C The most spectacular find, at Monte Verde in southern Chile, produced striking evidence of tool making, house building, rock painting, and human footprints conservatively dated long before
12、 the highway had been cleared of ice. D Many archaeologists now believe that migrants moved south in boats along a coastal route rather than overland. These people were probably gatherers and fishers rather than hunters of big game. There were two later migrations into North America. About 5000 b.c.
13、e. the Athapascan or Na-Dene people began to settle the forests in the northwestern area of the continent. Eventually Athapascan speakers, the ancestors of the Navajos and Apaches, migrated across the Great Plains to the Southwest. The final migration began about 3000 B.C.E after Beringa had been su
14、b merged, when a maritime hunting people crossed the Bering Straits in small boats. The Inuits (also known as the Eskimos) colonized the polar coasts of the Arctic, the Yupiks the coast of southwestern Alaska, and the Aleuts the Aleutian Islands. While scientists debate the timing and mapping of the
15、se migrations, many Indian people hold to oral traditions that include a long journey from a distant place of origin to a new homeland. 1 The word distinctive in the passage is closest in meaning to （ A） new （ B） simple （ C） different （ D） particular 2 According to paragraph 2, why did Stone Age tri
16、bes begin to migrate into Beringia? （ A） To intermarry with tribes living there （ B） To trade with tribes that made tools （ C） To hunt for animals in the area （ D） To capture domesticated dogs 3 The phrase Accompanied by in the passage is closest in meaning to （ A） Found with （ B） Joined by （ C） Thr
17、eatened by （ D） Detoured with 4 The word which in the passage refers to （ A） migrations （ B） evolution （ C） geneticists （ D） populations 5 Why does the author mention “blood types“ in paragraph 3? （ A） Blood types offered proof that the migration had come from Scandinavia. （ B） The presence of type
18、B in Native Americans was evidence of the migration. （ C） The blood typing was similar to data from both Japan and Scandinavia. （ D） Comparisons of blood types in Asia and North America established the date of migration. 6 How did groups migrate into the Great Plains? （ A） By walking on a corridor c
19、overed with ice （ B） By using the path that big game had made （ C） By detouring around a huge ice sheet （ D） By following a mountain trail 7 Why does the author mention the settlement at Monte Verde, Chile, in paragraph 5? （ A） The remains of boats suggest that people may have lived there. （ B） Arti
20、facts suggest that humans reached this area before the ice melted on land. （ C） Bones and footprints from large animals confirm that the people were hunters. （ D） The houses and tools excavated prove that the early humans were intelligent. 8 The word Eventually in the passage is closest in meaning t
21、o （ A） In the end （ B） Nevertheless （ C） Without doubt （ D） In this way 9 Which of the sentences below best expresses the information in the highlighted statement in the passage? The other choices change the meaning or leave out important information. （ A） Beringia was under water when the last peop
22、le crossed the straits in boats about 3000 B.C.E. （ B） Beringia sank after the last people had crossed the straits in their boats about 3000 B.C.E. （ C） About 3000 b.c.e., the final migration of people in small boats across Beringia had ended. （ D） About 3000 b.c.e., Beringia was flooded, preventing
23、 the last people from migrating in small boats. 10 According to paragraph 6, all of the following are true about the later migrations EXCEPT （ A） the Athapascans traveled into the Southwest United States. （ B） the Eskimos established homes in the Arctic polar region. （ C） the Aleuts migrated in smal
24、l boats to settle coastal islands. （ D） the Yupiks established settlements on the Great Plains. 11 Which of the following statements most accurately reflects the authors opinion about the settlement of the North American continent? （ A） The oral traditions do not support the migration theory. （ B） T
25、he anthropological evidence for migration should be reexamined. （ C） Migration theories are probably not valid explanations for the physical evidence. （ D） Genetic markers are the best evidence of a migration from Asia. 12 Look at the four squares that show where the following sentence could be inse
26、rted in the passage. Newly excavated early human sites in Washington State, California, and Peru have been radiocarbon dated to be 11,000 to 12,000 years old. Where could the sentence best be added? Click on a square to insert the sentence in the passage. 13 An introduction for a short summary of th
27、e passage appears below. Complete the summary by selecting the THREE answer choices that mention the most important points in the passage. Some sentences do not belong in the summary because they express ideas that are not included in the passage or are minor points from the passage. This question i
28、s worth 2 points. There is considerable evidence supporting a theory of multiple migrations from Asia to the Americas. - - - Answer Choices A Ancient stories of migrations from a faraway place are common in the cultures of many Native American nations. B The people who inhabited Monte Verde in south
29、ern Chile were a highly evolved culture as evidenced by their tools and homes. C Genetic similarities between Native American peoples and Asians include the arrangement of teeth, viruses, and blood types. D Hunters followed the herds of big game from Beringia south along the Rocky Mountains into wha
30、t is now called the Great Plains. E Excavations at archaeological sites provide artifacts that can be used to date the various migrations that occurred by land and sea. F The climate began to get warmer and warmer, melting the glacial ice about 13,000 b.c.e. 13 “Physical and Chemical Properties and
31、Changes“ Sugar, water, and aluminum are different substances. Each substance has specific properties that do not depend on the quantity of the substance. Properties that can be used to identify or characterize a substance and distinguish that substance from other substances are called characteristic
32、 properties. They are subdivided into two categories: physical properties and chemical properties. The characteristic physical properties of a substance are those that identify the substance without causing a change in the composition of the substance. They do not depend on the quantity of the subst
33、ance. A Color, odor, density, melting point, boiling point, hardness, metallic luster or shininess, ductility, malleability, and viscosity are all characteristic physical properties. For example, aluminum is a metal that is both ductile and malleable. B Another example of a physical property is wate
34、r. Whether a small pan of water is raised to its boiling point or a very large kettle of water is raised to its boiling point, the temperature at which the water boils is the same value, 100 degrees C or 212 degrees F. C Similarly, the freezing point of water is 0 degree C or 32 degrees F. These val
35、ues are independent of quantity. D Characteristic properties that relate to changes in the composition of a substance or to how it reacts with other substances are called chemical properties. The following questions pertain to the chemical properties of a substance. 1. Does it burn in air? 2. Does i
36、t decompose (break up into smaller substances) when heated? 3. What happens when it is placed in an acid? 4. What other chemicals will it react with, and what substances are obtained from the reaction? Characteristic physical and chemical properties also called intensive properties are used to ident
37、ify a substance. In addition to the characteristic physical properties already mentioned, some intensive physical properties include the tendency to dissolve in water, electrical conductivity, and density, which is the ratio of mass to volume. Additional intensive chemical properties include the ten
38、dency of a substance to react with another substance, to tarnish, to corrode, to explode, or to act as a poison or carcinogen (cancer-causing agent). Extensive properties of substances are those that depend on the quantity of the sample, including measurements of mass, volume, and length. Whereas in
39、tensive properties help identify or characterize a particular kind of matter, extensive properties relate to the amount present. If a lump of candle wax is cut or broken into smaller pieces, or if it is melted (a change of state), the sample remaining is still candle wax. When cooled, the molten wax
40、 returns to a solid. In these examples, only a physical change has taken place; that is, the composition of the substance was not affected. When a candle is burned, there are both physical and chemical changes. After the candle is lighted, the solid wax near the burning wick melts. This is a physica
41、l change; the composition of the wax does not change as it goes from solid to liquid. Some of the wax is drawn into the burning wick where a chemical change occurs. Here, wax in the candle flame reacts chemically with oxygen in the air to form carbon dioxide gas and water vapor. In any chemical chan
42、ge, one or more substances are used up while one or more new substances are formed. The new substances produced have their own unique physical and chemical properties. The apparent disappearance of something, like the candle wax, however, is not necessarily a sign that we are observing a chemical ch
43、ange. For example, when water evaporates from a glass and disappears, it has changed from a liquid to a gas (called water vapor), but in both forms it is water. This is a phase change (liquid to gas), which is a physical change. When attempting to determine whether a change is physical or chemical,
44、one should ask the critical question: Has the fundamental composition of the substance changed? In a chemical change (a reaction), it has, but in a physical change, it has not. Glossary ductility: can be drawn into wire malleability: can be shaped viscosity: thick, resistant to flow 14 According to
45、paragraph 1, what do physical properties and chemical properties have in common? （ A） They are both used to create most of the substances. （ B） They include basic substances like sugar and water. （ C） They are classified as characteristic properties of substances. （ D） They change in proportion to t
46、he amount of the substance. 15 The word pertain in the passage is closest in meaning to （ A） compare （ B） relate （ C） explain （ D） change 16 The word which in the passage refers to （ A） properties （ B） tendency （ C） density （ D） ratio 17 According to the passage, a “carcinogen“ will （ A） explode und
47、er pressure （ B） conduct electricity （ C） cause cancer （ D） tarnish in air 18 Which of the sentences below best expresses the information in the highlighted statement in the passage? The other choices change the meaning or leave out important information. （ A） Properties that are classified as inten
48、sive identify the type of substance and the extent of it present in the surrounding matter. （ B） The quantity of a substance influences its extensive properties, but the characteristics of the substance define the intensive properties. （ C） Where the intensive and extensive properties are found in s
49、ubstances is important in identifying their characteristics. （ D） Both intensive and extensive properties tend to have quantitative rather than qualitative characteristics present. 19 In paragraph 8, the author contrasts the concepts of physical and chemical changes by （ A） listing several types for each concept （ B） providing clear definitions for them （ C） identifying the common characteristics （ D） using a wax candle as an example 20 The word remaining in the passage is closest in meaning to （ A） hidden （ B） cut （ C） changed （ D） left 21 What can be inferred about phas
