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[英语四级阅读模拟训练附答案和精讲] 英语四级阅读模拟训练附答案和精讲 第51篇:动物中的睡眠
Sleep is very ancient. In the electroencephalographic(脑电图的)sense we share it with all the primates(灵长类动物)and almost all the other mammals and birds: it may extend back as far as the reptiles(爬行动物).2015-03-16 编辑：wendy
