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
答案是C，我选的D，谁能讲讲乎？ 作者: 花子落落 时间: 2010-8-6 04:43
Female rhinoceroses that have been frequently recollared 和uncollared females对比 如果说后者也经常因为其他原因被镇静剂麻醉的话 那么怎么解释两者之间存在的significantly lower fertility rates呢？所以说如果镇静剂只因为装那个radio collars时候使用其它情况不用，那就strengthen;反之，就说明这个繁殖力的差异并非镇静剂导致的，而是其它某些原因，weaken作者: iporcelain 时间: 2010-8-16 15:21
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