杭州新概念英语培训-312. How it came about that snakes manufactured poison is a mystery.
        蛇是怎样产生毒液的，这是一个谜。
313. Over the periods their saliva, a mild, digestive juice like our own,
        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，
314. was converted into a poison that defies analysis even today.www.51jjcn.cn/xgn/4221.html
        演变成了今天仍无法分析清楚的毒液。
315. It was not forced upon them by the survival competition;
        毒液不是生存竞争强加给它们的，
316. they could have caught and lived on prey without using poison,
        它们也可以不用毒液捕捉动物而生存，
317. just as the thousands of non-poisonous snakes still do.
        就像今天成千上万的无毒蛇那样。
318. Poison to a snake is merely a luxury;
        毒液对毒蛇来说只不过是一种舒适生存的优越手段，
319. it enables it to get its food with very little effort,
        它使蛇不用费多大力气就能捕获到食物，
320. no more effort than one bite.
       轻咬一口即可。
杭州新概念英语培训- 321. And why only snakes?
        为什么只有蛇才有毒液呢？
322. Cats, for instance, would be greatly helped;
        譬如说，如果猫有毒液，那对猫会大有帮助，
323. no running fights with large, fierce rats or tussles with grown rabbits
        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，
324. In fact, it would be an assistance to all carnivores
        因此，任何食肉动物有了毒液，都能从中获益。
325. though it would be a two-edged weapon when they fought each other.
        不过，当它们相互撕打时，毒液就成了利弊参半的武器，可以杀死对方，也可以被对方的毒液杀死。
326. But, of the vertebrates, unpredictable Nature ed only snakes (and one lizard).

学校名称：杭州优朗国际英语培训学校-杭州新概念英语培训