GRE阅读里的动物迷惑行为

在GRE阅读逻辑单题里面经常出现动物迷惑行为这样的主题，题目一般要求解释原因。这种题一般要抓住原文呈现的迷惑之处，找到一个答案要能够说明好事为什么变坏事，或者坏事为什么能变好事的。

例1:

Bats hunt for their prey, including moths, by emitting ultrasonic squeaks and analyzing the echoes. Arctiid moths are unusual in that they emit distinctive ultrasonic noises of their own in response to the hunting squeaks of bats, thereby giving away their location to the bats. These facts support the hypothesis that the moths protect themselves somehow by revealing their whereabouts to the bats.

Which of the following, if true, provides the strongest additional support for the hypothesis given?

A. Arctiid moths produce their ultrasonic noises with a special membrane that is permanently silenced if it is physically damaged.

B. Arctiid moths react to artificial bat squeaks in much the same way that they react to squeaks actually emitted by bats.

C. Arctiid moths are more colorful and more strikingly patterned than are many other kinds of moth.

D. Arctiid moths, like all other moths, are promptly killed if they get caught by hunting bats.

E. Arctiid moths taste very unpleasant to bats but are the same general shape and size as moths that bats like to eat.

迷惑：一种蛾子通过把自己的位置信息暴露给敌人的方式来保护自己。要加强就是说暴露了位置信息以后确实有好处，前四个答案都没什么用，E说蝙蝠不喜欢吃这种蛾子，但是这种蛾子又跟蝙蝠喜欢吃的长得像，就是很容易被误吃，所以它刻意暴露自己的位置信息，这样蝙蝠就知道是不好吃的蛾子在那边就不去了，蛾子保护了自己。

例2:

Crows, herring gulls, and sparrows all live on the island of Firsten. Crows feed on sparrow eggs and therefore pose a threat to the sparrow population. Although gull are not nearly as good at finding sparrow nest as crows are, sparrows typically also lose some eggs to gull predation. Nevertheless, sparrows that nest near gull nests tend to lose fewer eggs to predator than sparrows  nesting far away from gull nests, since_____.

1. Which of the following most logically completes tire argument?

the presence of gulls frightens away crows

crows pose no threat to adult sparrows

Gulls find sparrow nests by watching female sparrow enter the nest

there are far more crows on Firsten than there are sparrows.

Sparrows on Firsten typically hide their nests very carefully.

乌鸦、海鸥和麻雀都生活在Firsten岛上。乌鸦以麻雀蛋为食，因此对麻雀的数量构成了威胁。虽然海鸥不像乌鸦那样善于发现麻雀的巢穴，但麻雀通常也会因为海鸥的捕食而丢失一些蛋。尽管如此，在鸥巢附近筑巢的麻雀往往比在远离鸥巢的地方筑巢的麻雀因捕食而损失的蛋少，因为_____。

迷惑之处是为什么挨着坏人的反而过得更好。那就是坏人可能也有好作用。所以选A，海鸥会吓跑乌鸦，就是能对麻雀起到保护作用。而且乌鸦是大坏人，海鸥是小坏人，挨着海鸥相当于交点保护费。

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