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 ________.

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 ________.

IQ（intelligence quotient智商）is a score that shows a person’s level of intelligence.
People used to believe that some people are born with a high IQ and some aren’t.
  32 , a study by scientist at University College London has challenged（挑戰(zhàn)）this idea. According to an article last October on the Journal Nature, scientists are beginning to think that our IQ is not a constant（不變的）score.
The scientists tested 33 healthy young people in 2004 between the ages of 12 and 16. Then they did tests again four years later, when the same people were between 16 and 20.
Scientists found big changes in the IQ scores between 2008 and 2004. Some  33 and some fell  34 as many as 21 points.
To test whether these scores were meaningful, the scientists compared them with results from brain scans（掃描）. They found that the IQ changes matched changes in the structure（結構）of the subjects’ brains. “A change in 20 points is a huge  35 ,” said Professor Cathy Price, who led the research. He said it could mean the difference between an average and a  36 person. The team has not found a clear cause for these changes. However, they say it is  37 that education plays a role in changing IQ.
“Here we have shown that children’s  38 is likely to be still developing, ” says Price. “We have to be careful not to write off  39 performers at an early stage. In fact, their IQ may improve in a few more years. ”

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.

1.During REM sleep, a person’s breathing and heartbeat ________.

A．stop   B．increase     C．decrease   D．stay the same

2.Which word in paragraph（段落）3 means “colorful and lively”?

A．easier         B．empty         C．vivid   D．quickly

3.Which paragraph tells what happens when people don’t get enough sleep?

A．1         B．2         C．3         D．4

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.

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