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牛津7A英语试卷Unit6单元
How much sleep do we need? We are all different. Some people need only three or four hours of sleep a night. Others need ten hours of sleep a night. Most Americans sleep an average(平均) of seven to eight hours a night. After age fifty, the average sleep time goes down to 6.5 hours a night.
Most people have a night when they cannot sleep. About one in three Americans has a problem with sleep. Many of these people cannot fall asleep. The name of this problem is insomnia.
How much sleep do we need? We are all different. Some people need only three or four hours of sleep a night. Others need ten hours of sleep a night. Most Americans sleep an average(平均) of seven to eight hours a night. After age fifty, the average sleep time goes down to 6.5 hours a night.
Most people have a night when they cannot sleep. About one in three Americans has a problem with sleep. Many of these people cannot fall asleep. The name of this problem is insomnia.
