During the rest of sleep，the fatigue of the body disappears and recuperation（复原，恢复）begins．The tired mind gathers new energy；the memory improves；and annoyance and problems are seen in better perspective．
Some adults require little sleep，others need eight to ten hours in every twenty-four．Infants sleep sixteen to eighteen hours daily，the amount gradually diminishing as they grow older．Young students may need twelve hours；university students may need ten．A worker with a physically demanding job may also need ten ，whereas an executive working under GREat pressure may manage on six to eight．Many famous people are reputed to have required little sleep．Napoleon Bonaparte，Thomas Edison，and Charles Darwin apparently averaged only four to six hours a night．
Whatever your individual need，you can be sure that by the age of thirty you will have slept for a total of more than twelve years．By that age you will also have developed a sleep routine：a favorite hour，a favorite bed，a favorite posture，and a formula you need to follow in order to rest comfortably．
Investigators have tried to find out how long a person can go without sleep．Several people have reached more than 115 hours—nearly five days．Whatever the limit，it is absolute．Animals kept a wake for from five to eight days have died of exhaustion．The limit for human beings is probably about a week．
1．The writer implies that _______．
A）sleep is important for good mental and physical health
B）a light sleep is as restful as a deep sleep
C）memory is relatively unimportant for human beings
D）sleep is relatively unimportant for human beings
2．From the amount of sleep Napoleon，Edison，and Darwin required，we can conclude ________．
A）that they were famous B）that they were executives
C）that they were intelligent D）None of the above
3．The amount of sleep required may _________．
A）vary GREatly from one individual to another
B）depend on an individual's age
C）be related to an individual's occupation
D）All of the above
4．If a person is not allowed to follow his before-sleep routine，he will probably _______．
A）not sleep well B）never fall asleep
C）lose his memory D）begin to daydream
5．The longest time a human being can survive without sleep is probably ________．
A）five days B）seven days
C）ten days D）twelve days
6．Translate the underlined sentences in the paragraph 2 into Chinese．
参考答案：ADDAB
翻译：一个从事需要费体力的工作的工人每天也需要10小时的睡眠，而一位在很大压力下工作的总经理每天有6—8小时就行了。许多名人都曾以需要睡眠甚少而著称于世。
