A unique laboratory at the University of Chicago is busy only at night. It is a dream【C1】_

A unique laboratory at the University of Chicago is busy only at night. It is a dream【C1】______where researchers are at work studying dreamers. Their findings have revealed that everyone dreams from three to seven times a night,【C2】______ in ordinary life a person may remember none or only one of his dreams. While the【C3】______ sleep, special machines record their brain waves and eye movements as well as the body movements that【C4】______ the end of a dream. Surprisingly, all subjects【C5】______ soundly. Observers report that a person usually fidgets before a dream. Once the dream has started, his body relaxed and his eyes【C6】______ more active, as if the curtain had gone on a show. As soon as the machine【C7】______ that the dream is over, a buzzer wakens the sleeper. He sits up, records his dream, and goes back to sleep—perhaps to【C8】______ some more. Researchers have found that if the dreamer is【C9】______ immediately after his dream, he can usually recall the entire dream. If he is allowed to sleep even five more minutes his【C10】______ of the dream will have faded.

【C1】

A．mill

B．laboratory

C．hospital

D．classroom

请帮忙给出正确答案和分析，谢谢！