[外语类试卷]清华大学考博英语模拟试卷3及答案与解析.doc
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1、清华大学考博英语模拟试卷 3及答案与解析 一、 Reading Comprehension 0 Eight times within the past million years, something in the Earths climatic equation has changed, allowing snow in the mountains and the northern latitudes to accumulate from one season to the next instead of melting away. Each time, the enormous ice s
2、heets resulting from this continual buildup lasted tens of thousands of years until the end of each particular glacial cycle brought a warmer, climate. Scientists speculated that these glacial cycles were ultimately driven by astronomical factor; slow, cyclic changes in the eccentricity of the Earth
3、s orbit and in the tilt and orientation of its spin axis. But up until around 30 years ago, the lack of an independent record of ice-age timing made the hypothesis untestable. Then in the early 1950s Emiliani produced the first complete record of the waxings and wanings of first glaciations. It came
4、 from a seemingly odd place, the seafloor. Single-cell marine organisms called “foraminifera“ house themselves in shells made from calcium carbonate. When the foraminifera die, sink to the bottom, and become part of seafloor sediments, the carbonate of their shells preserves certain characteristics
5、of the seawater they inhabited. In particular, the ratio of a heavy isotope of oxygen (oxygen -18) to ordinary oxygen (oxygen -16) in the carbonate preserves the ratio of the two oxygens in water molecules. It is now understood that the ratio of oxygen isotopes reflects the proportion of the worlds
6、water locked up in glaciers and ice sheets. A kind of meteorological distillation accounts for the link. Water molecules containing the heavier isotope tend to condense and fall as precipitation slightly sooner than molecules containing the lighter isotope. Hence, as water vapor evaporated from warm
7、 oceans moves away from its source, its oxygen - 18 returns more quickly to the oceans than does its oxygen - 16. What falls as snow on distant ice sheets and mountain glaciers is relatively depleted of oxygen -18. As the oxygen -18 - poor ice builds up, the oceans become relatively enriched in the
8、isotope. The larger the ice sheets grow, the higher the proportion of oxygen -18 becomes in seawater and hence in the sediments Analyzing cores drilled from seafloor sediments, Emiliani found that the isotopic ratio rose and fell in rough accord with the Earths astronomical cycles. Since that pionee
9、ring observation, oxygenisotope measurements have been made on hundreds of cores. The combined record enables scientists to show that the record contains the very periodicities as the orbital processes. Over the past 800, 000 years, the global ice volume peaked every 100, 000 years, matching the per
10、iod of the orbital eccentricity variation. In addition, “ wrinkles“ superposed on each cycle small decreases or surges in ice volume have come at intervals of roughly 23, 000 and 41, 000 years, in keeping with the precession and tilt frequencies of the Earths spin axis. 1 In opening paragraph, the a
11、uthor introduces his topic by_ ( A) unfolding a phenomenon. ( B) posing a contrast ( C) refuting a speculation. ( D) testifying a hypothesis. 2 The expression “waxings and wanings“ (Paragraph 2) most probably means_ ( A) regularities and eccentricities. ( B) vaporizations and sediments. ( C) variant
12、s and constants. ( D) maximizations an minimizations. 3 As pointed out in the text, the ratio of oxygen -18 to oxygen -16 in seafloor sediments and that of these isotopes locked in glaciers and ice-sheets are_ ( A) irrelevant ( B) correlated. ( C) corresponding. ( D) identical. 4 Single-cell marine
13、organisms referred to as “ foraminifera“ as mentioned in the text might serve as_ ( A) a proof against the existence of oxygen -16. ( B) a testimony to sediment formation processes. ( C) a valid record justifying glacial periodic cycles. ( D) an indicator of the ratio of the two oxygens. 5 What can
14、we safely infer from the text? ( A) Many a phenomenon might be caused by astronomical factors. ( B) Any hypothesis should be abandoned unless supported by solid records. ( C) Glaciers are the records keeping Earths astronomical cycles. ( D) Oxygen isotopes are evenly distributed throughout the earth
15、 surface. 5 If you smoke and you still dont believe that theres a definite between smoking and bronchial troubles, heart disease and lung cancer, then you are certainly deceiving yourself. No one will accuse you of hypocrisy. Let us just say that you are suffering from a bad case of wishful thinking
16、. This neednt make you too uncomfortable because you are in good company. Whenever the subject of smoking and health is raised, the governments of most countries hear no evil, see no evil and smell no evil. Admittedly, a few governments have taken timid measures. In Britain, for example, cigarette a
17、dvertising has been banned on television. The conscience of the nation is appeased, while the population continues to puff its way to smoky, cancerous death. You dont have to look very far to find out why the official reactions to medical findings have been so lukewarm. The answer is simply money. T
18、obacco is a wonderful commodity to tax. Its almost like a tax on our daily bread. In tax revenue alone, the government of Britain collects enough from smokers to pay for its entire educational facilities. So while the authorities point out ever so discreetly that smoking may, conceivably, be harmful
19、, it doesnt do to shout too loudly about it This is surely the most short-sighted policy you could imagine. While money is eagerly collected in vast sums with one hand, it is paid out in increasingly vaster sums with the other. Enormous amounts are spent on cancer research and on efforts to cure peo
20、ple suffering from the disease. Countless valuable lives are lost In the long run, there is no doubt that everybody would be much better-off if smoking were banned altogether. Of course, we are not ready for such drastic action. But if the governments of the world were honestly concerned about the w
21、elfare of their peoples, youd think theyd conduct aggressive antismoking campaigns. Far from it! The tobacco industry is allowed to spend staggering sums on advertising. Its advertising is as insidious as it is dishonest We are never shown pictures of real smokers coughing up their lungs early in th
22、e morning. That would never do. The advertisements always depict virile, clean-shaven young men. They suggest it is manly to smoke, even positively healthy! Smoking is associated with the great open-air life, with beautiful girls, true love and togetherness. What utter nonsense! For a start, governm
23、ents, could begin by banning all cigarette and tobacco advertising and should then conduct anti-smoking advertising campaigns of their own. Smoking should be banned in all public places like theatres, cinemas and restaurants. Great efforts should be made to inform young people especially of the dire
24、 consequences of taking up the habit A horrific warning say, a picture of a deaths head should be included in every packet of cigarettes that is sold. As individuals we are certainly weak, but if governments acted honestly and courageously, they could protect us from ourselves. 6 The best title of t
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