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标题: 请教牛人 [打印本页]

作者: kevin_ws 时间: 2004-4-6 23:08
标题: 请教牛人
The dwarf masked owl, a rare migratory bird of prey, normally makes its winter home on the Baja peninsula, where it nests in the spiny cactus. In fact, there are no other suitable nesting sites for the dwarf masked owl on the Baja peninsula. But a blight last spring destroyed all of the spiny cacti on the Baja peninsula. So unless steps are taken to reestablish the spiny cactus population, the dwarf masked owl will not make its home on the Baja peninsula this winter.

The argument depends on assuming which one of the following?

(A) No birds of prey other than the dwarf masked owl nest in the spiny cactus.

(B) If the Baja peninsula contains spiny cacti, then the dwarf masked owl makes its winter home there.

(C) On occasion the dwarf masked owl has been known to make its winter home far from its normal migratory route.

(D) The dwarf masked owl will not make its winter home on the Baja peninsula only if that region contains no spiny cacti.

(E) Suitable nesting sites must be present where the dwarf masked owl masked its winter home.

请牛人帮忙解释一下为什么选E啊，选A有什么不对的啊

作者: 睡熊 时间: 2004-4-7 00:25
一个搭桥型假设，不知道从何解释。要不然你先说说为什么(A)对吧，然后我再告诉你错在哪里了。

作者: weiyu 时间: 2004-4-7 00:33

DMO在-->cactus nest在；　A属于out of scope. 别的鸟无关．

D混淆了充分必要条件

只有E是假设

作者: kevin_ws 时间: 2004-4-8 17:33
A不是NOT加削弱吗，请解释一下怎么搭的桥梁，之间缺什么联系啊，谢谢

作者: linchechin 时间: 2004-4-8 20:32
我被D選項迷惑了,請問weiyu兄,可否講一下本題的充分和必要條件??感激不盡!!!

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