阅读理解It's clear that everyone needs to sleep. Most people rar

阅读理解
It's clear that everyone needs to sleep. Most people rarely think about how and why they sleep, however. We know that if we sleep well, we feel rested. If we don't sleep enough, we often feel tired and irritable. It seems there are two purposes of sleep: physical rest and emotional and psychological rest. We need to rest our bodies and minds. Both are important in order for us to be healthy. Each night we alternate between two kinds of sleep: active sleep and passive sleep. The passive sleep gives our body the rest that's needed and prepares us for active sleep, in which dreaming occurs. Throughout the night, people alternate between passive and active sleep. The brain rests, then it becomes active, then dreaming occurs. The cycle is repeated: the brain rests, then it becomes active, then dreaming occurs. This cycle is repeated several times throughout the night. During eight hours of sleep, people dream for a total of one and half hours on the average.




We know all the following Except______.
单选题
A. A. How and why we sleepy.
B. B. If we sleep well, we feel rested.
C. C. If we sleep less, we often feel tired.
D. D. Everyone needs to sleep.

We have two kinds of sleep, __________.
单选题
A. A. physical and psychological
B. B. bodies and minds
C. C. active and passive
D. D. good sleep and absent sleep

In which kind of sleep dreams occur?
单选题
A. A. the active sleep
B. B. the passive sleep
C. C. good sleep
D. D. absent sleep

How many hours do people usually dream?
单选题
A. A. eight hours
B. B. one hour and a half
C. C. several hours
D. D. None is right

Choose a best title for this passage.
单选题
A. A. Passive Sleep
B. B. Active Sleep
C. C. Purpose of Sleep
D. D. Sleep