单选题 Directions: After reading the following passage, you will find 5 questions or unfinished statements, numbered 36 through 40. For each question or statement there are 4 choices marked A, B, C and D. You should make the correct choice and mark the corresponding letter on the Answer Sheet with a single line through the center.
No one knows why we sleep, but it's certain that we need to. People who are prevented from sleeping begin to suffer obvious effect after a few days — they think less clearly, and they fall asleep during the working hours. Some may have hallucinations (幻觉).
There are no rules about sleep. Generally speaking, grown-ups sleep about seven and a half hours each night and probably more than 60 percent get between seven and eight hours. But perhaps eight percent are quite happy with five hours or less, and four percent or so find that they want ten hours or more. If you feel all right, you're probably getting enough sleep. The important thing is not to worry how much other people get — their needs may be different. Exercise doesn't seem to increase the need for sleep, office workers, for example, sleep for about as long as people doing physically active work.
Children sleep more than grown-ups — perhaps fourteen to eighteen hours soon after birth, going down to grown-up levels by early teenage. Sleep patterns also tend to be different in the elderly, who may sleep less at night than they did when younger. They find sleep getting more broken, and often make it a rule to sleep during the daytime.

单选题 According to the passage, some people are unable to think clearly because ______.

A.they have hallucinations
B.they feel sleepy during the working hours
C.they don't have enough sleep
D.they sleep for too many hours

【正确答案】 C

【答案解析】

单选题 Which of the following is true?

A.All grown-ups must have at least eight-hour sleep.
B.Most grown-ups sleep for seven to eight hours.
C.Few grown-ups need only five hours or less to sleep.
D.Grown-ups usually sleep less than ten hours.

【正确答案】 B

【答案解析】

单选题 Whether you have enough sleep can be judged by ______.

A.how many hours you have slept
B.comparing with others
C.whether you do office work or physical work
D.whether you feel fresh and energetic

【正确答案】 D

【答案解析】

单选题 According to the passage, a boy of fourteen years old sleeps ______.

A.as many hours as a grown-up
B.much longer hours than a grown-up
C.for fourteen hours each day
D.for less than eight hours each day

【正确答案】 A

【答案解析】

单选题 Which of the following is true when the elderly find sleep getting more broken?

A.They just ignore it.
B.They usually sleep during the daytime.
C.They talk about it to their friends.
D.They are always complaining about it.

【正确答案】 B

【答案解析】