编辑点评: 研习GRE作文考试的优秀范文不仅可以学到有用的词汇和句子,更能从中学习逻辑的构建方式和作文框架的结构等内容,这里为大家提供GRE的范文,希望对同学们的备考有所帮助。
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 Middies 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.
体坛英语资讯:Britain falls in love again with cricket after World Cup victory: PM May
Boycott the Pornography Websites 抵制黄色网站
体坛英语资讯:FC Barcelona officially present new signing Antoine Griezmann
踏遍世界新七大奇迹
体坛英语资讯:Lakers star Davis withdraws from mens basketball World Cup in China
LV老板超越盖茨成为世界第二富
日本发明机器熊 翻转头部可治打鼾
国际英语资讯:Feature: Timely satellite data from China helps India combat floods
浪费生命、蹉跎人生的50件事III
体坛英语资讯:Tour of Qinghai Lake spearheads development of cycling in China
青少年游戏爱好者大脑结构和赌徒类似
My Favorite City—Zhuhai 我最喜欢的城市——珠海
娱乐英语资讯:Feature: Free Chopin concerts in the park in center Warsaw
国际英语资讯:Texas mass shooting treated as domestic terrorism case: U.S. attorney
体坛英语资讯:Im only at 60 percent of my potential, says NBA MVP Antetokounmpo
英国新任首相鲍里斯去见女王了
国际英语资讯:Spotlight: Consecutive mass shootings hit U.S., invoking pain, anger
四川大学老师要用熊猫粪便种世界上最贵茶叶
超有创意的烛台设计 让你舍不得点亮
最老牌的美国热狗是哪一家?
体坛英语资讯:Impey claims stage 9 win, Alaphilippe retains overall lead in Tour de France
国际英语资讯:4 people killed, 200 houses damaged in Indonesia strong quake
体坛英语资讯:Djokovic beats Federer to win his fifth Wimbledon title
宠爱女孩儿的20条理由
不忍直视!印度7岁男孩嘴里多长了526颗牙齿
美国人1/5听力受损 会干扰日常交流
浪费生命、蹉跎人生的50件事IV
体坛英语资讯:Chinas mixed pair qualifies for finals in artistic swimming of FINA worlds
甘肃正宁校车事故致20名幼儿死亡
国际英语资讯:News Analysis: U.S. Mideast peace plan doomed to failure without Palestinians consent: exp