新东方背诵50篇——托福听力专用(2)

明 这种分类显然是不适当的。美洲一种小型蜥蜴和沙漠鬣蜥同属冷血动物，但实际上它们的体温通常只比人类的体温低1～2度，因此并不是真正的冷血。因此又出现 了恒温动物(即保持恒定体温的动物)和变温动物(即体温随外界环境的变化而改变的动物)这一区分方式。但这种分类也不恰当。因为有不少哺乳动物在冬眠期间 会改变体温，而许多生活在深海的无脊椎动物在寒冷的深海水域中体温并不变化，而是恒定的。

Sleep 睡眠

2009-09-30 来源: 【大 中 小】 我要投稿

下载音频 划词已开启 Sleep is part of a person’s daily activity cycle. There are several different stages of sleep, and they too occur in cycles. If you are an average sleeper, your sleep cycle is as follows. When you fist drift off into slumber, your eyes will roll about a bit, you temperature will drop slightly, your muscles will relax, and your breathing well slow and become quite regular. Your brain waves slow and become quite regular. Your brain waves slow down a bit too, with the alpha rhythm of rather fast waves 1 sleep. For the next half hour or so, as you relax more and more, you will drift down through stage 2 and stage 3 sleep. The lower your stage of sleep. slower your brain waves will be. Then about 40to 69 minutes after you lose consciousness you will have reached the deepest sleep of all. Your brain will show the large slow waves that are known as the delta rhythm. This is stage 4 sleep.

You do not remain at this deep fourth stage all night long, but instead about 80 minutes after you fall into slumber, your brain activity level will increase again slightly. The delta rhythm will disappear, to be replaced by the activity pattern of brain waves. Your eyes will begin to dart around under your closed eyelids as if you were looking at something occurring in front of you. This period of rapid eye movement lasts for some 8 to 15 minutes and is called REM sleep. It is during REM sleep period, your body will soon relax again, your breathing will slip gently back from stage 1 to stage 4 sleep----only to rise once again to the surface of near consciousness some 80 minutes later.

睡眠是人每天日常活动循环的一部分。人的睡眠分几个阶段，而这些阶段也是循环发生的。如果你是一个正常的睡眠者，你的睡眠循环会这样进行。

在你开始昏昏入睡时，你的眼睛会滚动几下，体温略有下降，肌肉放松，呼吸变得缓慢而有节奏。除了开始几分钟比较快的α节奏外，脑电波也稍有减缓。 这被称为第一阶段睡眠。在随后约半小时内，你进一步放松，进入第二和第三阶