1、大学英语六级改革适用（阅读）模拟试卷 250及答案与解析 Section C 0 Wild Bill Donovan would have loved the Internet The American spymaster who built the Office of Strategic Services in World War and late laid the roots for the CIA was fascinated with information. Donovan believed in using whatever tools came to hand in the “g
2、reat game“ of espionage spying as a “profession“. These days the Net, which has already remade such everyday pastimes as buying books and sending mails, is reshaping Donovans vocation as well. The latest revolution isnt simply a matter of gentlemen reading other gentlemens e-mail. That kind of elect
3、ronic spying has been going on for decades. In the past three or four years, the World Wide Web has given birth to a whole industry of point-and-click spying. The spooks call it “open-source intelligence“, and as the Net grows, it is becoming increasingly influential. In 1995 the CIA held a contest
4、to see who could compile the most data about Burundi. The winner, by a large margin, was a tiny Virginia company called Open Source Solutions, whose clear advantage was its mastery of the electronic world. Among the firms making the biggest splash in this new world is Stratford, Inc., a private inte
5、lligence-analysis firm based in Austin, Texas. Stratford makes money by selling the results of spying (covering nations from Chile to Russia) to corporations like energy-services firm McDermott International. Many of its predictions are available online at www. Stratford, com. Stratford president Ge
6、orge Friedman says he sees the online world as a kind of mutually reinforcing tool for both information collection and distribution, a spymasters dream. Last week his firm was busy vacuuming up data bits from the far comers of the world and predicting a crisis in Ukraine. “As soon as that report run
7、s, well suddenly get 500 new Internet sign-ups from Ukraine,“ says Friedman, a former political science professor. “And well hear back from some of them.“ Open-source spying does have its risks, of course, since it can be difficult to tell good information from bad. Thats where Stratford earns its f
8、ame. Friedman relies on a lean staff of 20 in Austin. Several of his staff members have military-intelligence backgrounds. He sees the firms outsider status as the key to its success. Stratfords briefs dont sound like the usual Washington back-and-forthing, whereby agencies avoid dramatic declaratio
9、ns on the chance they might be wrong. Stratford, says Friedman, takes pride in its independent voice. 1 What can we learn about Bill Donovan? （ A） He was skilled in searching information in the Internet. （ B） He used to serve the CIA during the Second World War. （ C） He took the “great game“ of espi
10、onage as a profession. （ D） He had a new job that was closely related with the Net. 2 What is becoming increasingly influential as it is pointed out in the second paragraph? （ A） The industry of spying. （ B） The World Wide Web. （ C） The data found in the Net. （ D） The latest Net revolution. 3 In the
11、 third paragraph, Chile and Russia are two countries _. （ A） in which Stratford finds its major clients （ B） which McDermott International cooperates with （ C） about which Stratford finds information for its clients （ D） whose development has been boosted by Stratfords predictions 4 What makes Strat
12、ford the most successful spying firm is that _. （ A） it can find relevant data from any corner of the world （ B） it uses the Net in collecting and distributing information （ C） it is able to distinguish the good information from the bad （ D） it gets much feedback from the clients from all over the w
13、orld 5 It can be inferred that people use back-and-forthing in order to _. （ A） be independent of any influence （ B） make an official declaration （ C） apologize for any mistakes （ D） shift any possible blame 5 We sometimes think humans are uniquely vulnerable to anxiety, but stress seems to affect t
14、he immune defenses of lower animals too. In one experiment, for example, behavioral immunologist (免疫学家 ) Mark Laudenslager, at the University of Denver, gave mild electric shocks to 24 rats. Half the animals could switch off the current by turning a wheel in their enclosure, while the other half cou
15、ld not. The rats in the two groups were paired so that each time one rat turned the wheel it protected both itself and its helpless partner from the shock. Laudenslager found that the immune response was depressed below normal in the helpless rats but not in those that could turn off the electricity
16、. What he has demonstrated, he believes, is that lack of control over an event, not the experience itself, is what weakens the immune system. Other researchers agree. Jay Weiss, a psychologist at Duke University School of Medicine, has shown that animals who are allowed to control unpleasant stimuli
17、 dont develop sleep disturbances or changes in brain chemistry typical of stressed rats. But if the animals are confronted with situations they have no control over, they later behave passively when faced with experiences they can control. Such findings reinforce psychologists suspicions that the ex
18、perience or perception of helplessness is one of the most harmful factors in depression. One of the most startling examples of how the mind can alter the immune response was discovered by chance. In 1975 psychologist Robert Ader at the University of Rochester School of Medicine conditioned (使形成条件反射
19、) mice to avoid saccharin (糖精 ) by simultaneously feeding them the sweetener and injecting them with a drug that while suppressing their immune systems caused stomach upsets. Associating the saccharin with the stomach pains, the mice quickly learned to avoid the sweetener. In order to extinguish thi
20、s dislike for the sweetener, Ader reexposed the animals to saccharin, this time without the drug, and was astonished to find that those mice that had received the highest amounts of sweetener during their earlier conditioning died. He could only speculate that he had so successfully conditioned the
21、rats that saccharin alone now served to weaken their immune systems enough to kill them. 6 Laudenslagers experiment showed that the immune system of those rats who could turn off the electricity _. （ A） was strengthened （ B） was not affected （ C） was altered （ D） was weakened 7 According to the pass
22、age, the experience of helplessness causes rats to _. （ A） try to control unpleasant stimuli （ B） turn off the electricity （ C） behave passively in controllable situations （ D） become abnormally suspicious 8 The reason why the mice in Aders experiment avoided saccharin was that_. （ A） they disliked
23、its taste （ B） it affected their immune systems （ C） it led to stomach pains （ D） they associated it with stomachaches 9 The passage tells us that the most probable reason for the death of the mice in Aders experiment was that_. （ A） they had been weakened psychologically by the saccharin （ B） the s
24、weetener was poisonous to them （ C） their immune systems had been altered by the mind （ D） they had taken too much sweetener during earlier conditioning 10 It can be concluded from the passage that the immune systems of animals _. （ A） can be weakened by conditioning （ B） can be suppressed by drug i
25、njections （ C） can be affected by frequent doses of saccharin （ D） can be altered by electric shocks 10 If you go down to the woods today, you may meet high-tech trees genetically modified to speed their growth or improve the quality of their wood. Genetically-engineered food crops have become incre
26、asingly common, albeit controversial, over the past ten years. But genetic engineering of trees has lagged behind. Part of the reason is technical. Understanding, and then altering, the genes of a big pine tree are more complex than creating a better tomato. While tomatoes sprout happily, and rapidl
27、y, in the laboratory, growing a whole tree from a single, genetically altered cell in a test tube is a tricky process that takes years, not months. Moreover, little is known about tree genes. Some trees, such as pine trees, have a lot of DNA roughly ten times as much as human. And, whereas the Human
28、 Genome Project is more than half-way through its task of isolating and sequencing the estimated 100, 000 genes in human cells, similar efforts to analyze tree genes are still just saplings (幼苗 ). Given the large number of tree genes and the little that is known about them, tree engineers are starti
29、ng with a search for genetic “markers“. The first step is to isolate DNA from trees with desirable properties such as insect resistance. The next step is to find stretches of DNA that show the presence of a particular gene. Then, when you mate two trees with different desirable properties, it is sim
30、ple to check which offspring contain them all by looking for the genetic markers. Henry Amerson, at North Carolina State University, is using genetic markers to breed fungal resistance into southern pines. Billions of these are grown across America for pulp and paper, and outbreaks of disease are ex
31、pensive. But not all individual trees are susceptible. Dr. Amersons group has found markers that distinguish fungus-resistant stock from disease-prone trees. Using traditional breeding techniques, they are introducing the resistance genes into pines on test sites in America. Using genetic markers sp
32、eeds up old-fashioned breeding methods because you no longer have to wait for the tree to grow up to see if it has the desired traits. But it is more a sophisticated form of selective breeding. Now, however, interest in genetic tinkering (基因修补 ) is also gaining ground. To this end, Dr. Amerson and h
33、is colleagues are taking part in the Pine Gene Discovery Project, an initiative to identify and sequence the 50,000-odd genes in the pine trees genome Knowing which gene does what should make it easier to know what to alter. 11 Compared with genetic engineering of food crops, genetic engineering of
34、trees _. （ A） began much later （ B） has developed more slowly （ C） is less useful （ D） was less controversial 12 What does the author think about the genetic engineering of pine trees? （ A） Time-consuming. （ B） Worthwhile. （ C） Significant. （ D） Technically impossible. 13 What can we learn about the
35、 research on tree genes? （ A） The research methods are the same as the analysis of human genes. （ B） The findings are expected to be as fruitful as the analysis of human genes. （ C） It will take as much time and effort as the analysis of human genes. （ D） The research has been mainly concentrated on
36、 the genes of young trees. 14 It is discovered by Henry Amersons team that _. （ A） southern pines cannot resist fungus （ B） all southern pines are not susceptible （ C） the genetic marker in southern pines was the easiest to identify （ D） fungus-resistant genes came originally from outside the U.S.A.
37、 15 What is the primary objective of carrying out the Pine Gene Discovery Project? （ A） To speed up old-fashioned breeding methods. （ B） To identify all the genes in the pine trees genome. （ C） To find out what desired traits the pine trees have. （ D） To make it easier to know which gene needs alter
38、ing. 15 If our solar system has a Hell, its Venus. The air is choked with foul and corrosive sulfur, heaved from ancient volcanoes and feeding acid clouds above. Although the second planet is a step farther from the sun than Mercury, a runaway greenhouse effect makes it hotter indeed. Its the hottes
39、t of the nine plants, a toasty 900 degrees Fahrenheit of baking rocky flats from equator to poles. All this under a crushing atmospheric pressure 90 times that of where youre sitting now. From the earthly perspective, a dead end. It must be lifeless. “Venus has nothing,“ is the blunt word from plane
40、tologist Kevin Zahnle of NASA Ames Research Center in Californias Silicon Valley. “Weve written it off.“ Yet a small group of advanced life-forms on Earth begs to differ, and theorizes that bizarre microbial ecosystems might have once populated Venus and, in fact, may be there still. Members of this
41、 loose band of researchers suggest that their colleagues have water too much on the brain, and are, in a sense, H2O chauvinists (盲目的爱国者 ). “Astrobiologists are neglecting Venus due more to narrow thinking than actual knowledge of the environment, or environments, where life can thrive,“ says Dirk Sc
42、hulze-Makuch, a geobiologist at the University of Texas at El Paso who recently co-authored a Venus-boosting paper in Astrobiology with colleague Louis Irwin. The bias against life on Venus is partly rooted in our own biology. Human experience instructs that liquid water, preferably lot of it, is es
43、sential for life. In search for extraterrestrial life, we obsess over small rivers in Mars surface apparently carved by ancient gushes of water, and delight in hints of permafrost (永久冻结带 ) just underneath its surface. (By comparison, Venus isnt even that interesting to look at: A boring cue ball (台球
44、的白色母球 ) for backyard astronomers, its clouds reflects 75% of visible light) Attention and then funding follow the water. Three more landers will depart for Mars this spring, and serious plans for sample-return missions hover in the midterm future. “If you have limited resources, you base exploration
45、 on what you know,“ says Arizona State University planetary geologist Ronal Greeley. Its like losing your keys on the way home at night: The first place you look is under the streetlights not because theyre more likely to be there, but because if they are, youll spot them. For astrobiologists, the s
46、treetlights are the spectral (光谱的 ) lines for water, and theyve spotted that potential on Mars, Jupiters moon Europa, even Neptunes moon Triton. Not on the baking rocky flats of Venus. 16 Venus is the hottest of all the nine planets in the solar system because_. （ A） it is not so close to the sun as
47、 Mercury （ B） many volcanoes spread the whole planet （ C） it is covered by a thick layer of cloud （ D） greenhouse effect is uncontrollable on it 17 Some planetologists believed there had never been lives on Venus because _. （ A） they couldnt find any trace of water on it （ B） they found Venus is too
48、 hot for any lives （ C） Venus is covered by dirty and poisonous cloud （ D） Venus is the second nearest planet to the sun 18 It can be inferred from the passage that the small group of advanced life-forms on Earth believed that _. （ A） life could exist in hot environment （ B） life could exist without
49、 water （ C） there are still lives on Venus （ D） there used to be lives on Mars 19 What do we learn from the passage about Venus and Mars? （ A） The atmospheric pressure of Venus is stronger than that of Mars. （ B） Venus attracts more attention and funding than Mars. （ C） Venus is closer to the sun than Mars. （ D） Venus looks more beautiful than Mars. 20 The purpose of the co-authored paper by Dirk Schulze-Makuch and Louis Irwin was to _. （ A） introduce their findings about Venus （
