求助一道PREP上面的原题，感谢大家了

Cherliuiking

Every fall Croton's jays migrate south.  The jays always join flocks of migrating crookbeaks with which they share the same summer and winter territories.  If a jay becomes separated from the crookbeaks it is accompanying, it wanders until it comes across another flock of crookbeaks.  Clearly, therefore, Croton's jays lack the navigational ability to find their way south on their own.

Which of the following, if true, most strengthens the argument above?

A. Croton's jays lay their eggs in the nests of crookbeaks, which breed upon completing their southern migration.

B. The three species most closely related to crookbeaks do not migrate at all.

C. In the spring, Croton's jays migrate north in the company of Tattersall warblers.

D. Species other than Croton's jays occasionally accompany flocks of migrating crookbeaks.

E. In the spring, crookbeaks migrate north before Croton's jays do.
答案选A，为什么呢？

wu0h961738

kluivert 发表于 2018-9-13 15:33
题目结论是：这种鸟没向南迁徙的导航能力

C选项直接否定了这种鸟有导航能力（不管向东南西北） ，都得跟 ...

本串唯一標準答案

jackslin

感谢分享！               

TuesdayA

我又来啦！
来自Ron:
" ok, i see what you guys are saying. so, it's time to apply the reasonableness test - which of these two is more reasonable? let's simplify this:

which of the following is more likely to strengthen the idea that the jays cannot fly south on their own?
(c) they can't fly north on their own, either.
(e) they CAN fly north on their own.

in this simplified version, it should be obvious that (c) is better than (e)."

kluivert

题目结论是：这种鸟没向南迁徙的导航能力

C选项直接否定了这种鸟有导航能力（不管向东南西北） ，都得跟着别的鸟飞

E说crookbeaks比这种鸟先向北迁徙 ，这不能说明任何问题。纯粹无关 ... 在E的前提下，这种鸟有可能自己稍后自己飞回北方，又或跟着别的鸟飞

TuesdayA

跟楼上的两位同胞想到一块儿去了～

VikingYu

suk1yan 发表于 2017-7-12 11:44
感觉题目有问题呀~到底题目是以“这种鸟找不着南”作为结论，还是以“这种鸟没有方向感”作为结论？如果以 ...

同意这两种差异的划分！


如果，题目给的结论只是——这种鸟找不着南
那么，由于C佐证的是鸟找不着北；所以C应该属于无关选项，无法加强原论证……

换一个例子
前提：小花每次去幼儿园都要妈妈陪，妈妈不在她就等妈妈来了才去幼儿园
结论：小花没有从家里到幼儿园的方向感

这时候“小花从家到楼下小卖部需要爸爸陪”，貌似没办法说明“小花没有从家里到幼儿园的方向感”吧……

suk1yan

感觉题目有问题呀~到底题目是以“这种鸟找不着南”作为结论，还是以“这种鸟没有方向感”作为结论？如果以前者的“这种鸟找不着南”为结论，（也是题目的意思），只要选出能证明它“找得着北”的选项就可以了。那么E选项说：这种鸟回北方的时候不需要同伴陪同（带路），即能找得找北，就是正确选项。如果结论是“这种鸟没有方向感”为结论，才是选的C。

猪小王

小皮麽西瓜 发表于 2014-6-26 07:31
刚好在看寂静碰到这道题。。如果问strengthens就选C，因为C中说jays它再返回北方时还是要跟着别人才能回 ...

同意！               

一只酵母君

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