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单选题The word "offset" in the second paragraph could be replaced by ______.

单选题At present groups of scientific workers, often (26) by their governments, spend their time in (27) the (28) of earthquakes. It is very (29) that they will be able to (30) earthquakes or influence the direction of their movements, which are determined by events far below the surface of the earth. But the facts they report and the theories (31) by those facts may enable scientists to (32) the centers of future earthquakes and even (33) the time of their (34) . It is only when the (35) of events that we call an earthquake can be seen as a pattern that predictions can be made. Part of this pattern is external and (36) or capable of being recorded by (37) instruments above the earth's surface. Scientists and engineers studied the (38) of the San Francisco earthquake. The city was re built, and new features were (39) to strengthen buildings and maintain a (40) water supply in the event of another earthquake. The water mains (=main pipes) were fitted with control valves which would enable water to travel by different routes round broken places. Large underground tanks were constructed to supply water if (41) supplies could not be tapped. Special measures were (42) to prevent fires, which often do more damage than earthquakes themselves. The San Francisco earthquake (43) scientists with important information. Since the effects of the break were visible at the surface, scientists could (44) what actually happened, and reports of the incident were an important (45) to the world's store of knowledge about earthquakes.

单选题According to scientists, people sneeze because ______.

单选题Wheredoestheconversationmostprobablytakeplace?

单选题 Questions 19—22 are based on the following passage. You now have 20 seconds to read the questions 19—22.

单选题[此试题无题干]

单选题听下面一段对话，回答第22至第25题。

单选题 IQuestions 18-21 are based on the following dialogue./I

单选题There was one thought that air pollution affected only the area immediately around large cities with factories and heavy automobile traffic. At present, we realize that although these are the areas with the worst air pollution, the problem is literally worldwide. On several occasions over the past decade, a heavy cloud of air pollution has covered the east of the United States and brought health warnings in rural areas away from any major concentration of manufacturing and automobile traffic. In fact, the very climate of the entire earth may be infected by air pollution. Some scientists consider that the increasing concentration of carbon dioxide in the air resulting from the burning of fossil fuels (coal and oil)is creating a "greenhouse effect" —conserving heat reflected from the earth and raising the world's average temperature. If this view is correct and the world's temperature is raised only a few degrees, much of the polar ice cap will melt and cities such as New York, Boston, Miami, and New Orleans will be in water. Another view, less widely held, is that increasing particular matter in the atmosphere is blocking sunlight and lowering the earth's temperature—a result that would be equally disastrous. A drop of just a few degrees could create something close to a new ice age, and would make agriculture difficult or impossible in many of our top farming areas. Today we do not know for sure that either of these conditions will happen (though one recent government report drafted by experts in the field concluded that the greenhouse effect is very possible). Perhaps, if we are lucky enough, the two tendencies will offset each other and the world's temperature will stay about the same as it is now. Driven by economic profit, people neglect the damage on our environment caused by the "advanced civilization". Maybe the air pollution is the price the human beings have to pay for their development. But is it really worthwhile?

单选题{{I}}Questions 14 -17 are based on the following dialogue.{{/I}}

单选题The phrase "build on "in the last parapraph most probably means " ______ ".

单选题Questions 11-14 are based on a conversation about exercising．

单选题 IQuestions 22 ～ 25 are based on the following conversation between a daughter and her father./I

单选题The advantage of employees having foreign language skills is that they can ______.