求解一道GRE逻辑题!为什么正确答案是E?2.Spiders of many species change color to match the pigmentation of the flowers they sit on.The insects preyed on by those spiders,unlike human beings,possess color discrimination so acute that they

求解一道GRE逻辑题!为什么正确答案是E?2.Spiders of many species change color to match the pigmentation of the flowers they sit on.The insects preyed on by those spiders,unlike human beings,possess color discrimination so acute that they
求解一道GRE逻辑题!为什么正确答案是E?
2.Spiders of many species change color to match the pigmentation of the flowers they sit on.The insects preyed on by those spiders,unlike human beings,possess color discrimination so acute that they can readily see the spiders despite the seeming camouflage.Clearly,then,it must be in evading their own predators that the spiders’ color changes are useful to them.Which of the following,if true,most strengthens the argument?
　　(A) Among the animals that feed on color- changing spiders are a few species of bat,which find their prey through sound echoes.
　　(B) Certain animals that feed on color-changing spiders do so only sparingly in order to keep from ingesting harmful amounts of spider venom.
　　(C) Color-changing spiders possess color discrimination that is more acute than that of spiders that lack the ability to change color.
　　(D) Color-changing spiders spin webs that are readily seen by the predators of those spiders.
　　(E) The color discrimination of certain birds that feed on color-changing spiders is no more acute than that of human beings.

求解一道GRE逻辑题!为什么正确答案是E?2.Spiders of many species change color to match the pigmentation of the flowers they sit on.The insects preyed on by those spiders,unlike human beings,possess color discrimination so acute that they
原文提供的信息如下：（1）有些蜘蛛会变色（2）但这些蜘蛛的猎物仍能清晰辨别蜘蛛,他们对色彩的辨别能力很强（不像人类这么弱!）（3）既然蜘蛛的变色不能帮助它们捕猎,那么变色的原因就只能是逃避天敌了.问：下面哪个陈述最能支持这种观点?
A 蜘蛛天敌中包括某些种类的蝙蝠,它们靠回声定位捕猎.【这并不能说明蜘蛛通过变色能更好地逃脱,所以不对】
B 有些吃变色蜘蛛的动物不敢多吃,怕中毒.【与问题无关】
C 变色蜘蛛比不变色的蜘蛛更能分辨颜色.【还是对逃跑没有帮助】
D 变色蜘蛛织的网很容易被捕食者发现.【还是与蜘蛛变色无关】
E 捕食变色蜘蛛的某些鸟类,其分辨颜色的能力并不比人类更好.【题目中提到了人类分辨颜色的水平不高,如果这些天敌也不怎么会分辨颜色,那么蜘蛛就可以通过变色逃脱了.注意：本文中的color discrimination应该是指透过变化的颜色看到本质的能力】

这道题的意思，你应该能看明白的。分析一下它的三句话：

1. 蜘蛛可以随着植物的颜色改变自身颜色（这是现象）

2. 被这些蜘蛛扑食的昆虫视力并不像人类那么好（人类可以辨别蜘蛛伪装后的颜色）。（这句言外之意就是，即使蜘蛛不变色，猎物昆虫也能被捕食。蜘蛛变色对它捕食昆虫没有影响。否定了蜘蛛变色时为了隐蔽自己以便捕食昆虫这个观点）

3. 蜘蛛变色时为了躲避以它们为食物的猎食者。（提出新的观点）

    

   E只有人类才能精确地辨别颜色，看到经过颜色伪装后的蜘蛛。以蜘蛛为食的鸟的视力不如人类那么好。它就无法辨别伪装的和植物环境色一样的蜘蛛。所以蜘蛛可以躲过鸟的捕食。这样就支持了第3句话的观点。

A,bat，完全不影响
B,跟毒液没有关系
C,变色蛛比别的蛛对颜色敏感，对捕食者也没有影响，如bat
D,如果变色蛛可以被捕食者轻易看到，变色能力也没有逃避作用
E，捕食者色弱，那么可以因为变色增加逃生机会。