[外语类试卷]托福(阅读)模拟试卷14及答案与解析.doc
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1、托福(阅读)模拟试卷 14及答案与解析 一、 Sections Three: Reading Comprehension 0 “Four Stages of Planetary Development“ Planetary Development The planet Earth has passed through four-stages of planetary development. All terrestrial planets pass through these same stages to some degree, but some planets evolved furthe
2、r or were affected in different ways. The Four Stages The first stage of planetary evolution is differentiation, the separation of material according to density. Earth now has a dense core and a lower-density crust, and that structure must have originated very early in its history. Differentiation w
3、ould have occurred easily if Earth were molten when it was young. Two sources of energy could have heated Earth. First, heat of formation was released by in-falling material. A meteorite hitting Earth at high velocity converts most of its energy of motion into heat, and the impacts of a large number
4、 of meteorites would have released tremendous heat. If Earth formed rapidly, this heat would have accumulated much more rapidly than it could leak away, and Earth was probably molten when it formed. A second source of heat requires more time to develop. The decay of radioactive elements trapped in t
5、he Earth releases heat gradually; but, as soon as Earth formed, that heat began to accumulate and helped melt Earth. That would have helped the planet differentiate. While Earth was still in a molten state, meteorites could leave no trace, but in the second stage in planetary evolution, cratering, t
6、he young Earth was battered by meteorites that pulverized the newly forming crust. The largest meteorites blasted out crater basins hundreds of kilometers in diameter. As the solar nebula cleared, the amount of debris decreased, and after the late heavy bombardment, the level of cratering fell to it
7、s present low level. Although meteorites still occasionally strike Earth and dig craters, cratering is no longer the dominant influence on Earths geology. As you compare other worlds with Earth, you will discover traces of this intense period of cratering, on every old surface in the solar system. T
8、he third stage, flooding, no doubt began while cratering was still intense. The fracturing of the crust and the heating produced by radioactive decay allowed molten rock just below the crust to well up through fissures and flood the deeper basins. You will find such flooded basins with solidified la
9、va flows on other worlds, such as the moon, but all traces of this early lava flooding have been destroyed by later geological activity in Earths crust. On Earth, flooding continued as the atmosphere cooled and water fell as rain, filling the deepest basins to produce the first oceans. A Notice that
10、 on Earth flooding involves both lava and water, a circumstance that we will not find on most worlds. B The fourth stage, slow surface evolution, has continued for the last 3.5 billion years or more. C Earths surface is constantly changing as sections of crust slide over each other, push up mountain
11、s, and shift continents. D Almost all traces of the first billion years of Earths geology have been destroyed by the active crust and erosion. Earth as a Planet All terrestrial planets pass through these four stages, but some have emphasized one stage over another, and some planets have failed to pr
12、ogress fully through the four stages. Earth is a good standard for comparative planetology because every major process on any rocky world in our solar system is represented in some form on Earth. Nevertheless, Earth is peculiar in two ways. First, it has large amounts of liquid water on its surface.
13、 Fully 75 percent of its surface is covered by this liquid; no other planet in our solar system is known to have such extensive liquid water on its surface. Water not only fills the oceans but also evaporates into the atmosphere, forms clouds, and then falls as rain. Water falling on the continents
14、flows downhill to form rivers that flow back to the sea, and in so doing, the water produces intense erosion. You will not see such intense erosion on most worlds. Liquid water is, in fact, a rare material on most planets. Your home planet is special in a second way. Some of the matter on the surfac
15、e of this world is alive, and a small part of that living matter is aware. No one is sure how the presence of living matter has affected the evolution of Earth, but this process seems to be totally missing from other worlds in our solar system. Furthermore, the thinking part of life on Earth, humank
16、ind, is actively altering our planet. Glossary meteorite: a mass that falls to the surface of a planet from space planetology: the study of planets 1 Why does the author mention the “Earth“ in paragraph 1 ? ( A) To explain the stages in planetary development for the Earth in detail ( B) To contrast
17、the evolution of the Earth with that of other planets ( C) To demonstrate that the Earth passed through similar stages to those of most planets ( D) To give an example of exploration of the terrestrial planets 2 The word its in the passage refers to ( A) meteorite ( B) Earth ( C) velocity ( D) motio
18、n 3 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) The Earth may have been liquid because the heat collected faster than it dissipated if the formation took place q
19、uickly. ( B) Because of the rapid formation of the Earth, the crust took a long time to cool before it became a solid. ( C) The liquid core of the Earth was created when the planet first formed because the heat was so high and there was little cooling. ( D) The cooling caused the Earth to form much
20、more quickly as it met with the intense heat of the new planet. 4 The word pulverized in the passage is closest in meaning to ( A) melted into liquid ( B) broken into small parts ( C) frozen very hard ( D) washed very clean 5 The word dominant in the passage is closest in meaning to ( A) most limite
21、d ( B) most likely ( C) most rapid ( D) most important 6 What can be inferred about radioactive matter? ( A) It is revealed by later activity. ( B) It generates intense heat. ( C) It is an important stage. ( D) it floods the planets crust. 7 According to paragraph 4, how were the oceans formed? ( A)
22、 Ice gouged out depressions in the Earth. ( B) Rain filled the craters made by meteorites. ( C) Earthquakes shifted the continents. ( D) Molten rock and lava flooded the basins. 8 What is the authors opinion of life on other planets? ( A) She does not know whether life is present on other planets. (
23、 B) She is certain that no life exists on any planet except Earth. ( C) She does not express an opinion about life on other planets. ( D) She thinks that there is probably life on other planets. 9 According to the passage, which stage occurs after cratering? ( A) Flooding ( B) Slow surface evolution
24、 ( C) Differentiation ( D) Erosion 10 All of the following are reasons why the Earth is a good model of planetary development for purposes of comparison with other planets EXCEPT ( A) The Earth has gone through all four stages of planetary evolution. ( B) Life on Earth has affected the evolution in
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- 外语类 试卷 托福 阅读 模拟 14 答案 解析 DOC
