A Sleep is something we all do. But some people need to sleep more than others. Babies sleep most of the time. Children in school sleep about ten to twelve hours a night. Most adults sleep only seven or eight hours. But babies, children, and adults-all of us need to have our sleep. All parts of our bodies have to rest after they work. Our arms need a rest after we lift heavy things. When we are awake, they help us pay attention to the world around us. We can sit quite still and rest our arms and legs. But our brai aren’t resting. They go right on thinking as long as we are awake. Our brai slow down a bit when we sleep and dream. But even as we sleep our brai are doing some work. I tead of thinking wide-awake thoughts, our brai make up dreams. Some dreams are very pleasing. Some are not. Most of the time we forget them when we wake up. Scientists have tried to find out what would ha en if people were not allowed to sleep and to dream. They asked some people not to go to bed. The people stayed up all night and all the next day. They stayed up the next night too, and the day after. The people became very sleepy. They tried to read but could not follow the words. They played games, but they made mistakes. They forgot things. It was hard for their tired brai to work. The people grew rude and mean. They became angry with their friends. Finally they were too tired to stand up. When they sat down, they fell asleep. Scientists have found that if people are not allowed to sleep and to dream, they act strangely. No one knows quite why sleep is so good for us. But we do know that we beed it to stay well. So tonight have a good sleep. Shut your eyes. Let your thoughts wander. Soon you’ll stop thinking. You’ll be asleep. 44. Why do people need to sleep? Because_______________________. A. their arms need the rest B. their legs need the rest C. their brai need the rest D. all of the above 45. When we fall asleep ____________. A. our brai keep on working busily B. our brai stop to work. C. the work of our brai is much slower D. none of the above 46. Which of the following is true? A. We forget the dreams which are not very pleasing. B. While we sleep, our brai aren’t doing work. C. Sometimes our brai make up dreams when we sleep. D. Most of the time we make up dreams. 47. In this pa age we know _________________. A. most of us need to have our sleep B. Scientists have found out what will ha en to people if they are not allowed to sleep C. all parts of our bodies will stop to rest after they work D. people will act strangely if they don’t make up dreams