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题库 / OG2020-CR-621
According to a study, after a week of high-altitude living, twenty men had slimmed down.The men, middle-aged residents of low-altitude areas, had been taken to a research station at 2,650 meters (8,694 feet) above sea level. They had unrestricted access to food and were forbidden vigorous exercise, yet they lost an average of 1.5 kilograms (3.3 pounds) during their one-week stay. Clearly, the lower availability of oxygen at higher altitudes, or hypobaric hypoxia, can be said to have caused the weight loss, since __________.
Which of the following would, if true, most logically complete the argument?
a decrease in oxygen intake has been shown to depress appetite
the men all participated in the same kinds of exercise during their stay
the foods available to the men had fewer calories than the foods they usually ate
exercise at higher altitudes is more difficult than exercise at lower altitudes is
several weeks after returning home, the men still weighed less than they had before the study
情景：研究表明，在高纬度住一周后，20个住在低纬度的中年男人瘦了。他们在这期间能随便吃，不能做剧烈运动，但还是瘦了。很明显，高纬度缺氧气，所以他们瘦了，因为______。
推理：这种题目直接找出一个可以解释（加强）他们会瘦的原因。
选项分析：
A选项：正确。缺氧会导致没胃口：进一步明确了缺氧和变瘦之间的关系，缺氧使得没有胃口，吃得少就会瘦。
B选项：在这一周内所有男人都参加了同样的运动：无关。
C选项：这期间的食物比他们通常吃的食物的有更低的卡路里：此选项削弱了上述推论——如果这一周内的食物有更低的卡路里，那么或许变瘦就和缺氧没有关系了。
D选项：在高纬度锻炼比在低纬度锻炼更困难：与锻炼的难易度无关。
E选项：在回家后的几周这些男人还是比实验前瘦：此选项削弱了上述推论——按理说高纬度的缺氧导致了变瘦，但回家后如果还是瘦，可能就和缺氧无关了。
题目里边说了，没有限制他们的吃，不允许做剧烈运动，所以BCD无关，E是没办法解释在高纬度变瘦，A缺氧导致食欲不佳，吃得少了，所以瘦了。
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