四六级

　　转眼间，2017年6月英语六级考试已经近在眼前，在距离2017年6月英语六级考试还有一个来星期的时间里，文都网校小编提醒各位考生保持良好心态进行最后的冲刺复习！下面小编整理了英语六级考试阅读题冲刺模拟练习，各位考生要加油哦！

　　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 (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 could mot. 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 (使形成条件反射) 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 this 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 rats that saccharin alone now served to weaken their immune systems enough to kill them.

　　11. Laudenslager’s 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

　　12. According to the passage, 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

　　13. The reason why the mice in Ader’s experiment avoided saccharin was that ________.

　　A) they disliked its taste

　　B) it affected their immune systems

　　C) it led to stomach pains

　　D) they associated it with stomachaches

　　14. The passage tells us that the most probable reason for the death of the mice in Ader’s experiment was that ________.

　　A) they had been weakened psychologically by the saccharin

　　B) the sweetener was poisonous to them

　　C) their immune systems had been altered by the mind

　　D) they had taken too much sweetener during earlier conditioning

　　15. 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 injections

　　C) can be affected by frequent doses of saccharin

　　D) can be altered by electric shocks

　　参考答案：BCDCA

　　时间已经不多，练习还需加强，毕竟是实力决定成败，各位考生一定要努力哦！文都网校四六级频道预祝各位六级考试顺利！

　　另外，2017年6月大学英语四六级冲刺备考正在火热的进行中，文都网校将陪伴大家一起度过冲刺备考的关键时期！点击进入大学英语四六级冲刺备考专题>>，可与大家一起学习考试内容及最新辅导资料，还会有考前预测题和更多考试经验，惊喜连连，不可错过哦~