2019年英语六级考试口语短文背诵2

学习是一点点进步的过程，俗话说逆水行舟，不进则退，学习亦是如此。大家报考英语六级考试口语部分，就应该坚持自己的选择，不断探索，吸取知识。当然坦途网英语六级考试频道小编也会陪着大家度过考前艰难的备考时间，相信大家一定会有收获的。

睡眠的演化

Evolution of sleep

Sleep is very ancient. In the electroencephalographic sense we share it with all the primates and almost all the other mammals and birds: it may extend back as far as the reptiles.

There is some evidence that the two types of sleep, dreaming and dreamless, depend on the life-style of the animal, and that predators are statistically much more likely to dream than prey, which are in turn much more likely to experience dreamless sleep. In dream sleep, the animal is powerfully immobilized and remarkably unresponsive to external stimuli. Dreamless sleep is much shallower, and we have all witnessed cats or dogs cocking their ears to a sound when apparently fast asleep. The fact that deep dream sleep is rare among pray today seems clearly to be a product of natural selection, and it makes sense that today, when sleep is highly evolved, the stupid animals are less frequently immobilized by deep sleep than the smart ones. But why should they sleep deeply at all? Why should a state of such deep immobilization ever have evolved?

Perhaps one useful hint about the original function of sleep is to be found in the fact that dolphins and whales and aquatic mammals in genera seem to sleep very little. There is, by and large, no place to hide in the ocean. Could it be that, rather than increasing an animal’s vulnerability, the University of Florida and Ray Meddis of London University have suggested this to be the case. It is conceivable that animals who are too stupid to be quite on their own initiative are, during periods of high risk, immobilized by the implacable arm of sleep. The point seems particularly clear for the young of predatory animals. This is an interesting notion and probably at least partly true.

本文整理的六级口语短文背诵应该对大家很有帮助，口语就是不断练习，不断纠正发音的过程，每天朗读或者背诵一篇英语短文，不仅对大家的语言表达能力有提升，而且对语感也会很有帮助。大家只要想着以通过英语六级考试为目标，就会每日坚持下来，晨读背诵，相信很快就会有成效的。