单选题It is difficult to imagine what life would be like without memory. The meanings of thousands of everyday perceptions, the bases for the decisions we make, and the roots of our habits and skills are to be found in our past experiences, which are brought into the present by memory. Memory can be defined as the capacity to keep information available for later use. It includes not only "remembering" things like arithmetic or historical facts, but also involving any change in the way an animal typically behaves. Memory is involved when a rat gives up eating grain because he has sniffed something suspicious in the grain pile. Memory is also involved when a six-year-old child learns to swing a baseball bat. Memory exists not only in humans and animals but also in some physical objects and machines. Computers, for example, contain devices for storing data for later use. It is interesting to compare the memory-storage capacity of a computer with that of a human being. The instant-access memory of a large computer may hold up to 100,000 "words"—ready for instant use. An average U.S. teenager probably recognizes the meaning of about 100,000 words of English. However, this is but a fraction of the total amount of information which the teenager has stored. Consider, for example, the number of faces and places that the teenager can recognize on sight. The use of words is the basis of the advanced problem-solving intelligence of human beings. A large part of a person"s memory is in terms of words and combinations of words.

单选题It's high time we ______ something to stop traffic accidents. A. do B. will do C. did D. must do

单选题It is reported that the American Medical Association has called for the sport ofBoxing ______.A. to be forbiddenB. to be forbiddingC. to have been forbiddenD. to forbid

单选题She went on reading ______ it was midnight.

单选题What a pity! There are no tickets _____ for the coming concert.

单选题His father mentioned to me that Robert had written to him requesting money for buying a new car. A. to me B. had written to C. him D. for buying

单选题I hear ______ boys in your school like playing football in their spare time, though others prefer basketball.

单选题What we said at the meeting ______ little to the chairman. He refused to change his mind.

单选题His ______ of the aeroplane was correct in every detail and could really fly.

单选题If we (　　)our test tomorrow, I would have gone to the concert.

单选题Tom: Let's go picnic this Saturday. Susan: Don't you think it's still a bit chilly at this time of year? Tom: ________ .

单选题He _____ to have the examination yesterday evening, but he went to the concert instead.

单选题All parts of the house ______ the windows were in good condition.

单选题Few people nowadays are able to ________ friendship into their senior years.

单选题He couldn’t even rent a cheapest car, __________ this one．

单选题It was in 2005 ______ we began to introduce this new technique into our company.

单选题—Why do you think I am not popular among my classmates? —Maybe you don't talk about topics that interest them, ______ everything you say is friendly.