短文填空There is no living creature that doesn't need sleep or complete rest every day.If you want to know _1_ ,just go without sleep for a period of time! You would find it hard to _2_ on your ***.So everyone knows the _3_ of sleep.One of the things that we all know _4_ sleep is that we are unconscious in sleep. we don't know _5_ going on around us. But that doesn't _6_ the body stops all activities. The vital organs go on working during sleep,but most of the body functions slow down.Your body temperature becomes lower when you are _7_ ,so people always go to sleep under some kind of covers.And e