请教！新Prep1-74

74.   (29534-!-item-!-188;#058&004138)

In a certain wildlife park, park rangers are able to track the movements of many rhinoceroses because those animals wear radio collars.  When, as often happens, a collar slips off, it is put back on.  Putting a collar on a rhinoceros involves immobilizing the animal by shooting it with a tranquilizer dart.  Female rhinoceroses that have been frequently recollared have significantly lower fertility rates than uncollared females.  Probably, therefore, some substance in the tranquilizer inhibits fertility.

In evaluating the argument, it would be most useful to determine which of the following?

A. Whether there are more collared female rhinoceroses than uncollared female rhinoceroses in the park

B. How the tranquilizer that is used for immobilizing rhinoceroses differs, if at all, from tranquilizers used in working with other large mammals

C. How often park rangers need to use tranquilizer darts to immobilize rhinoceroses for reasons other than attaching radio collars

D. Whether male rhinoceroses in the wildlife park lose their collars any more often than the park’s female rhinoceroses do

E. Whether radio collars are the only practical means that park rangers have for tracking the movements of rhinoceroses in the park

答案选c，我选D，困惑中，请大家指点，谢谢！

UP

我也选D的

刚做完这题， 不知道说不说的清楚

1 Putting a collar on a rhinoceros involves immobilizing the animal by shooting it with a tranquilizer dart.

2 Female rhinoceroses that have been frequently recollared have significantly lower fertility rates than uncollared females.

结论： some substance in the tranquilizer inhibits fertility

简单的说就是

 1，A（Female rhinoceroses ） 有什么东东 （tranquilizer dart)

2，A能显现某种特征 (lower fertility rates) 而B(uncollared females)不能

结论：A有的这个东东使这种特征显

必须要证明B没有这种东东啊

那么选项c确实如我们所愿的提出了是不是还有别的什么可能用tranquilizer dart的情况

评价题.
题目说: 1. collar掉了要重新戴上; 2. 重新戴collar需要打tranquilizer; 3. 重新戴collar次数多的雌犀牛受孕率低
结论是: 可能是tranquilizer抑制受孕

选项:
D, 是否雄犀牛比雌犀牛丢collar的次数更多...从头到尾也没说雄犀牛...楼主想多了...而且无论是否都不影响结论...
C, 除戴collar之外的原因使用tranquilizer的次数?
如果次数很多, 比如, 重戴collar多的雌犀牛被shoot 10次, 没有重戴collar的因为其他原因被shoot 50次, 则不一定得出结论, 削弱
如果次数很少, 那么重戴collar多, 则被shoot的次数多, 则很可能是tranquilizer导致受孕率低, 加强..
典型的评价题答案

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