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单选题What can we learn from the last paragraph?

单选题 We sometimes think humans are uniquely vulnerable to anxiety, but stress seems to affect the immune defenses of lower animals too. In one experiment, for example, behavioral immunologist 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 could 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. 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 don' t 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 experience 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 mice to avoid saccharin 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 this dislike for the sweetener, Ader re-exposed 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 rats that saccharin alone now served to weaken their immune systems enough to kill them.

单选题We know we have to read "between the lines" to get the most out of anything. Making up is also a useful practice, 21 you shouldn"t mark up a book which isn"t yours. Librarian who 22 you books expect you to keep them clean, and you should .If you decide that I am right about the usefulness of marking books, you will have to 23 them. There are two ways in 24 one can own a book. The first is the property right you establish by 25 it, just as you pay for clothes and furniture. But the act of purchase is only the prelude to 26 .Full ownership comes only when you have made it a 27 of yourself, and the best way 28 yourself a part of it is by writing in it. An illustration may make the point clear. You buy a beefsteak and transfer it 29 the butcher"s icebox to you own. But you don"t own the beefsteak in the most important sense until you comsume it and get it 30 your bloodstream. I am arguing that books, too, must be absored in tour bloodstream 31 you any good. There are three kinds of book owners. The first has all the standard sets and best sellers—unread, 32 .The second has a 33 many books —few of them read 34 ,most of them dipped into, but all of them as clean and shiny 35 the day they were bought. The third has a few books or many—every one of them 36 and dilapidated. Why is 37 a book indispensable to reading? First, it keeps you awake. I mean wide 38 .In the second place, reading if it is active, is thinking, and thinking 39 express itself in words. Finally, writing helps you remember the thought you had, at the thoughts the author 40 .

单选题Questions 17～20 are based on a report about high style cameras. You now have 20 seconds to read Questions 17～20.

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单选题When receiving treatment, patients are always

单选题 Questions 14—16 are based on the following passage.

单选题The author includes the example about dogs to show that ______.

单选题Teachers are different in their opinions about

单选题What does the word "tedious" (Line 3, Para. 2) mean?

单选题Imagine waking up and finding the value of your assets has been halved. No, you"re not an investor in one of those hedge funds that failed completely. With the dollar slumping to a 26-year low against the pound, already-expensive London has become quite unaffordable. A coffee at Starbucks, just as unavoidable in England as it is in the United States, runs about $8. The once all-powerful dollar isn"t doing a Titanic against just the pound. It is sitting at a record low against the euro and at a 30-year low against the Canadian dollar. Even the Argentine peso and Brazilian real are thriving against the dollar. The weak dollar is a source of humiliation, for a nation"s self-esteem rests in part on the strength of its currency. It"s also a potential economic problem, since a declining dollar makes imported food more expensive and exerts upward pressure on interest rates. And yet there are substantial sectors of the vast U.S. economy-from giant companies like Coca-Cola to mom-and-pop restaurant operators in Miami-for which the weak dollar is most excellent news. Many Europeans may view the U.S. as an arrogant superpower that has become hostile to foreigners. But nothing makes people think more warmly of the U.S. than a weak dollar. Through April, the total number of visitors from abroad was up 6.8 percent from last year. Should the trend continue, the number of tourists this year will finally top the 2000 peak? Many Europeans now apparently view the U.S. the way many Americans view Mexico-as a cheap place to vacation, shop and party, all while ignoring the fact that the poorer locals can"t afford to join the merrymaking. The money tourists spend helps decrease our chronic trade deficit. So do exports, which thanks in part to the weak dollar, soared 11 percent between May 2006 and May 2007. For first five months of 2007, the trade deficit actually fell 7 percent from 2006. If you own shares in large American corporations, you"re a winner in the weak-dollar gamble. Last week Coca-Cola"s stick bubbled to a five-year high after it reported a fantastic quarter. Foreign sales accounted for 65 percent of Coke"s beverage business. Other American companies profiting from this trend include McDonald"s and IBM. American tourists, however, shouldn"t expect any relief soon. The dollar lost strength the way many marriages break up- slowly, and then all at once. And currencies don"t turn on a dime. So if you want to avoid the pain inflicted by the increasingly pathetic dollar, cancel that summer vacation to England and look to New England. There, the dollar is still treated with a little respect.