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The first flight of the Space Shuttle Columbia in the spring of 1981 was a revolutionary development in space exploration. Unlike the rockets of the previous twenty years, Columbia has the enormous advantages of being specially designed to return to earth and make further flights. Among a large number of projects scientists are investigating its future use. The most exciting, perhaps, is that the first steps can now be taken towards establishing human colonies in space. The present Space Shuttle can only stay in space for about a week, but it could take people out to build "islands" where they stay for longer periods. By the year 2050 scientists estimate that man will be able to construct permanent settlements.The first "islands" would be energy stations. There would be no hope of establishing colonies in space unless people could obtain energy there, instead of getting it from the earth. However, if the original could convert solar energy into electricity, it would be possible to provide the equivalent of a filling station for cars on earth, allowing the Space Shuttle to refuel and stay in orbit for longer periods of time.If this initial project were successful, much larger solar energy stations would be constructed later with materials brought out by the Shuttle.Eventually, man would be able to construct an "inhabitable planet" in space. According to the talk, what will man probably be able to do by the year 2050()
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M: How did you do on the examW: I passed, but I didn’t do so well. The essay question was the worst part for me. How about youM: I did all right on everything except the essay question, too. I wasn’t really prepared to write about the tribes in the rainforests of Brazil. We studied the rainforests for only a few days. I didn’t think it would be on the test.W: Me either. I thought for sure that he would ask us something about the Incas in Peru or maybe the mountain peoples in Chile. I studied most of the material on these groups and didn’t spend much time on the people of the rainforest. Do you know how much theexam counts towards our final gradeM: I think it’s 30 percent.W: Thirty percent! Oh no, I’m in deep trouble this time! That means I’ll have to get A’s on everything else to get a decent grade.M: That may not be too hard. We’ve already gone through most of the readings that the class is supposed to cover. After next week it will just be review. But then there is the final paper, of course.W: Yes. I was hoping to do well on this test so I could relax when writing my paper, but now it looks like I’ll have to spend more time preparing to write that paper.M: Well, I will too. Hey, I’m kind of hungry. I think I’ll go to get some lunch. Do you feel like joining meW: I’d love to, but I have to go home and study. I’ll call you later. What is the woman upset about()
夜间驾驶人对事物的观察能力明显比白天差。
北京某机械进出口公司从意大利某公司进口仪器两台．该仪器属于法检商品，实施自动许可管理和“一批一证制”管理。经海关批准，收货人申报前查看货物时发现货物与实际不符，并与该意大利某公司交涉。该意大利公司同意赔偿并重新发运一台与合同规定相同规格的仪器，要求收货人将不符合合同规定规格的仪器削价留购，收货人表示同意留购。按照以上所述对以下各题作出正确选项： 下列（）是海关对留购的仪器征收进口关税和代征税时适用的税率。
Only three strategies are available for controlling cancer: prevention, screening and treatment. Lung cancer causes more deaths than any other types of cancer. A major cause of the disease is not (21) known; there is no good evidence that screening is much helpful, and treatment (22) in about 90 percent of all cases. At present, therefore, the main strategy must be (23) . This may not always be true, of course, as for some other types of cancer, research (24) the past few decades has produced (or suggested) some importance in prevention, screening or treatment.(25) , however, we consider not what research may one day offer but what today’s knowledge could already deliver that is not being delivered, then the most practicable and cost-effective opportunities for (26) . premature death from cancer, especially lung cancer, probably involve neither screening nor improved (27) , but prevention.This conclusion does not depend on the unrealistic assumption that we can (28) tobacco. It merely assumes that we can reduce cigarette sales appreciably by raising prices or by (29) on the type of education that already appears to have a (30) effect on cigarette assumption by whitecollar workers and that we can substantially reduce the amount of tar (31) per cigarette. The practicability of preventing cancer by such measures applies not only in those countries, (32) , the United States of America, because cigarette smoking has been common for decades, 25 to 30 percent of all cancer deaths now involves lung cancer, but also in those where it has become (33) only recently. In China, lung cancer (34) accounts for only 5 to 10 percent of all cancer deaths. This is because it may take as much as half a century (35) the rise in smoking to increase the incidence to lung cancer. Countries where cigarette smoking is only now becoming widespread can expect enormous increase in lung cancer during the 1990’s or early in the next century, (36) prompt effective action is taken against the habit-indeed, such increase is already plainly evident in parts of the (37) .There are four reasons why the prevention of lung cancer is of such overwhelming importance: First, the disease is extremely common, causing more deaths than any other type of cancer now (38) ; Secondly, it is generally incurable; Thirdly, effective, practicable measures to reduce its incidence are already reliably known; and finally, (39) tobacco consumption will also have a substantial (40) on many other diseases. 35().
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