Do you know why you sleep? You may think it’s because you’re tired. Or perhaps you’ve been told sleep is good for you. Yet no one knows exactly why or how people sleep.
Until the early 1950s, most scientists thought the body and brain rested during sleep. Then a scientist watched people sleep. He noticed that during periods of between 5 and 30 minutes each, sleepers’ eyes made rapid movements, as if they were watching something. He called these periods REM sleep, for Rapid Eye Movement. Periods when sleepers’ eyes did not move he called non-REM sleep.
Whenever the scientist woke people during REM sleep, they were having vivid dreams. Measurements showed that sleepers’ pulses（脈搏）went up quickly during REM sleep. Their breathing, heartbeat, and the blood going to the brain also increased. Far from being a time of rest, REM sleep is a time when the body is hard at work. Scientists still don’t know the reason for this. Some believe REM sleep makes learning easier. Babies spend a lot of time in REM sleep. Because of this, some scientists believe that REM sleep helps the brain grow. Others think REM sleep is a time for the brain to empty the day’s garbage.
One thing all the scientists agree on is that sleep is necessary. Without enough sleep, people make mistakes. Most major car accidents happen during the early morning hours, when people are sleepiest.
【小題1】During REM sleep, a person’s breathing and heartbeat ________.

A．stopB．increaseC．decreaseD．stay the same
【小題2】Which word in paragraph（段落）3 means “colorful and lively”?
A．easierB．emptyC．vividD．quickly
【小題3】Which paragraph tells what happens when people don’t get enough sleep?
A．1B．2C．3D．4
【小題4】What is the main idea of the article?
A．REM sleep helps the brain grow.
B．REM sleep has been watched and recorded by scientists.
C．REM sleep is a time to empty the day’s garbage.
D．REM sleep is an active time when the body is hard at work.
【小題5】You can decide from the article that REM sleep ________.
A．has a restful effect on people
B．can be avoided with lots of sleep
C．is something that all people experience
D．is something that all scientists agree on


【小題1】B
【小題2】C
【小題3】D
【小題4】B
【小題5】A

解析【小題1】本文第三段提到人在REM睡眠階段，一個人的呼吸和心跳上升，故本題選B。
【小題2】第三段第一句的含義為人在REM睡眠階段，人會做五顏六色，多姿多彩的夢，vivid表示此意，故本題選C。
【小題3】本文第四段提到人們沒有得到足夠的睡眠，人們可能會犯錯誤，如車禍，故本題選D。
【小題4】本文第二段提到科學家觀察和記錄了人們的REM睡眠階段的有關(guān)情況，為本文的主要內(nèi)容，故本題選B。
【小題5】本文第二段提到人們在REM睡眠階段，人的身體和大腦會得到休息的效果，故本題選A。

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