After a day’s hard work, we need some sleep. During the sleep, the fatigue of the body

disappears and recuperation begins. The tired mind gathers new energy, and the memory improves.

Some adults require little sleep; others need eight to ten hours in every twenty-four hours. 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 pressure may manage on six to eight. Many famous people have 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 more than twelve years. By the age you will also have developed a sleep routine: a favorite hour, a favorite position, and a rule 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 awake for from five to eight days have died of exhaustion. The limit for human beings is probably about a week.

(1).By writing this passage, the writer intends to tell us 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 improved during sleep

D、sleep is relatively unimportant for human beings

(2).The amount of the sleep required may ___.

A、tire an individual mind

B、help infants grow older

C、apply pressure on an executive

D、that they didn’t sleep long

(3).If a person is not allowed to follow his own sleep routine, he will probably _____.

A、never fall sleep