Dreams may be influenced(影响) by different things that are present during sleep.If a person is cold,he may dream that he is out in a snowstorm.Worries or anger may also influence the content of a dream.?

Some people think that they seldom dream,other people are quite sure that they do not dream at all.Studies of human sleep have shown,though,that everyone dreams every night.If a person thinks he does not dream,it is because he does not remember dreaming when he wakes up.Usually,a person may dream three to seven times for a total of one to two hours of dreaming every night.?

Perhaps you are wondering just how research workers can be sure that a person is dreaming.The story behind the discovery is an interesting one.?

During their research studies of human sleep,Dr.Kleitman and his assistant noticed that a person sleeping made sudden eye movements.These movements occurred at least several times a night.When a sleeper was awakened during these periods of eye movement it was learned that he had been dreaming.In most cases,the dreamer could then recall(回忆) his dream.The person's eye movements,scientists believe,were caused by the movements of his eyes as he followed the events of the dream.?

Not only does everyone dream,but it seems that we all need to dream.One theory is that dreaming gives us a chance to escape from the rules of our real world.In dreams we can see our wishes come true.We can be rich,powerful,and successful.?

　　Another theory is that in our dream we are trying to work out problems that have troubled us during waking moments.?

　　Whatever the explanation is,we all do dream,and dreaming is necessary and important to us.?

1.According to the selection,the research studies of human sleep show_____.?

A.few people dream at night?

B.some people dream three times every night?

C.some people may dream all the time during sleep?

D.everyone dreams several times every night?

2.According to the research studies,you may dream of a fire-engine________.?

A.when your alarm clock is ringing?

B.when you feel hungry?

C.when you are cold?

D.when you are ill?

3.According to the selection,you can discover what a sleeping person is dreaming of by _____.?

A.watching him (her) closely?

B.waking him(her) up when he(she) makes sudden eye movements?

C.watching his(her) eye movements?

D.talking to him while he (she) is sleeping?

4.Dreaming is important to us_______.?

A.because scientists help us in our dreams?

B.because we can relax and enjoy a care free life in our dreams?

C.because we can have a good rest?

D.because we can make discoveries in our dreams?