Passage 2There is no creature that does not need sleep or complete rest every day.If you want to knowwhy, just try going without sleepfor a long period of time. You will discover thatyour mind and body would become loo tired to work properly. You would become imitable and find it hardto think clearly or concentrate on your work. So sleep is quite simply the time when the cells of your bodyrecover from the work of the day and build up supplies of energy for the next period of activity.One of the things we all know about sleep is that we are unconsciousin sleep. We do not know whatis going on around us. But that doesn't mean the body stops all activity. The important organs continue towork during sleep, but most of the body functions are slowed down.For example, our breathing becomes slower and deeper. The heart beats more slowly, and the bloodpressure is lower. Our arms and legs become limp and muscles are at rest. It would be impossible for ourbody to relax to such an extent if we were awake. So sleep does for us what the most quiet rest can not do.Your body temperature becomes lower when you are asleep, which is the reason people go to sleepunder some kind of covers. And even though you are unconscious, many of your reflexes still work. Forinstance, if someone tickles your foot, you will put it away in your sleep, or even brush a fly from yourforehead. You do these things without knowing it.66. If you don't have as much sleep as your body needs, you will ________ . A: work properly B: think clearly C: keep your attention on your work D: easily get angry