There is an endless supply of stories about sleepwalkers(梦游者). People have been said to climb on roofs, solve mathematical problems, write music, walk through windows, and do murder in their sleep.
In Revere, Massachusetts, a hundred policemen searched for a lost boy who left his home in his sleep and woke up five hours later on a strange sofa in a strange living room, with no idea how he had got there.
At the University of Lowa, a student was reported to have the habit of getting up in the middle of the night and walking three-quarters of a mile to the Lowa River. He would take a swim and then go back to his room to bed.
An American expert on sleep claims(声称) that he has never seen a sleepwalker. He is said to know more about sleep than any other living man, and during the last thirty-five years he has lost a lot of sleep watching people sleep. He says, “Of course, I know that there are sleepwalkers because I have read about them in the newspapers. But none of my sleepers ever walked, and if I were to advertise for sleepwalkers for an experiment, I doubt whether I would get many takers(应征者).”
Sleepwalking, however, is a scientific reality. It is one of those strange things that sometimes look quite fantastic(奇特的). Doctors say that sleepwalking is much more common than is generally supposed. Many sleepwalkers do not try to find help and their sleepwalking is never recorded.
Generally speaking, sleepwalkers are people who __________.

A．do fantastic things during their sleep

B．walk through windows

C．climb on roofs

D．walk in a half-awake state

It was reported that a boy ________.

A．was found on a strange sofa, telling how he had got there

B．lost his way five hours after he left home

C．slept in his own room but woke up in a strange room

D．was searched for by policemen when he lost his way

There was a college student who got into the habit of _______.

A．walking three-quarters of a mile every day

B．getting up in the middle of the night and walking down to the river

C．swimming in the Lowa River before going to bed

D．walking about before he went to bed

Why do people think sleepwalking is nothing but a fantastic thing which doesn’t have any explanation?

A．It is so common that it needn’t be recorded.

B．Scientists take no interest in it.

C．No records about it have been made.

D．Most sleepwalkers do not seek help for their problem.