The amount of sleep a human being needs depends on【C1】______ , the individual and possibly race. For example, doctors think that pre-school children need between 10 and 12 hours a night; school children between 9 and 11 hours; and adults between 7 and 9 hours. There are exceptional【C2】______ of old people who only sleep between 2 and 3 hours a day and continue to be active and healthy. The sleep requirements of different【C3】______ also appear to be different. Japanese people, for example, sleep fewer hours than Europeans. It is not known for【C4】______ if mental activity(apart from dreaming)occurs when a person is asleep.【C5】______ , it is certainly true that some people can wake up at a specific, predetermined time. There are also【C6】______ about mathematicians who solve difficult problems during sleep, because their【C7】______ minds continue working on the problem. Some types of unpleasant dreams(or 'nightmares')are quite【C8】______ ; the dreamer is taking a test, but is not properly prepared; he is falling from a tree;【C9】______ an animal or thing is chasing him. Some people say these last two occur【C10】______ mans ancestors lived in trees and were in constant danger from wild animals.
【C1】
A．gender
B．occupation
C．age
D．personality

未分类题【C7】 on

未分类题Our whole physical universe, when______to the simplest terms, is made up of two things, energy and matter.A．being reducedB．reducingC．reducedD．to be reduced

未分类题Water expands ______ freezing, as can be deduced from occasional breaks in water pipes in severe winters.A．onB．duringC．withD．against

未分类题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．millB．laboratoryC．hospitalD．classroom

未分类题Not everyone has this two-legged instrument, but everyone, with a little attention, may observe signs of that kind of fault-finding disposition and make the same resolution to avoid those______.A．infected with itB．infecting with itC．infected with themD．infecting with them

未分类题The work unit is more like a large family, ______the youngest workers feel at ease with the 'mum' and 'dad' of the group.A．whenB．whichC．whereD．whose

未分类题The soldier replied in a tone as angrily as ______, that he had lost his leg abroad in defense of those who did nothing at home.A．theyB．themC．theirD．theirs

未分类题The police discovered the thiefs hide-out two days later, ______, however, the thieves had disappeared.A．by that timeB．thenC．whenD．by which time

未分类题The lesson which gradually filtered through was the simple concept ______ every place has special meanings for the people in it; every place represents the center of the world.A．thatB．whichC．in whichD．from which

未分类题It is true that the old road is less direct and a bit bumpy. We wont take the new one______because we feel as safe on it.A．howeverB．thoughC．neverthelessD．whatsoever

未分类题Each of the built-in costs of a product must bring in some profit at each stage: truckers must profit from transporting products, or they______ in business.A．would not beB．will not beC．were notD．can not be

未分类题There is frequently a great interval between knowing how to solve a problem and______the resources to solve it.A．how to getB．to getC．getD．getting

未分类题From industrial beginnings in the nineteenth century, plastics______through a hundred and twenty years of glory, failure, disrepute and suspicion on the slow road to public acceptance.A．struggledB．have struggledC．are strugglingD．has struggled

未分类题The king made a promise______he would give the tailor both half of his kingdom and his daughter, but none the tailor had.A．whenB．onceC．thatD．since

未分类题So far environmental protection has left much room ______ ; lumbering and hunting have done immense damage to the environment.A．to be desiredB．to desireC．desiredD．for desiring