新概念英语第四册训练：Snake poison

2023-01-04 07:29:00来源：网络

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　　Snake poison

　　蛇毒

　　How it came about that snakes manufactured poison is a mystery. Over the

　　periods their saliva, a mild, digestive juice like our own, was converted into a

　　poison that defies analysis even today. It was not forced upon them by the

　　survival competition; they could have caught and lived on prey without using

　　poison, just as the thousands of non-poisonous snakes still do. Poison to a

　　snake is merely a luxury; it enables it to get its food with very little effort,

　　no more effort than one bite. And why only snakes? Cats, for instance, would be

　　greatly helped; no running fights with large, fierce rats or tussles with grown

　　rabbits -- just a bite and no more effort needed. In fact, it would be an

　　assistance to all carnivores though it would be a two-edged weapon when they

　　fought each other. But, of the vertebrates, unpredictable Nature selected only

　　snakes (and one lizard). One wonders also why Nature, with some snakes,

　　concocted poison of such extreme potency.

　　蛇是怎样产生毒液的，这是一个谜。蛇的唾液本来和我们人的消化液一样柔和，但经过漫长的时间，演变成了今天仍无法分析清楚的毒液。毒液不是生存竞争强加给它们的，它们也可以不用毒液捕捉动物而生存，就像今天成千上万的无毒蛇那样。毒液对毒蛇来说只不过是一种舒适生存的优越手段，它使蛇不用费多大力气就能捕获到食物，轻咬一口即可。为什么只有蛇才有毒液呢?譬如说，如果猫有毒液，那对猫会大有帮助，它就不必再和又大又凶的老鼠边跑边博斗了，也不必再和大兔子扭斗了，只要咬一口，就不必再费大力气。因此，任何食肉动物有了毒液，都能从中获益。不过，当它们相互撕打时，毒液就成了利弊参半的武，可以杀死对方，也可以被对方的毒液杀死。然而，在脊椎动物中，大自然神秘模测地只选择了蛇(还有一种蜥蜴)，人们弄不清楚大自然为什么在某些蛇的身上调制出如此高效的毒液来。

　　New words and expressions 生词与短语

　　saliva

　　n. 唾液

　　digestive

　　adj. 助消化的

　　defy

　　v. 使不可能

　　analysis

　　n. 分析

　　prey

　　n. 被捕食的动物

　　fierce