某学校1999名学生去游故宫、景山和北海三地，规定每人至少去一处，至多去两地游览，那么至少有多少人游的地方相同
A．35
B．186
C．247
D．334
参考答案：D
解析： 根据题意，学生游玩的情况可能为{故宫}{景山}{北海}{故宫、景山}{故宫、北海}{景山、北海}共6种情况，1999÷6=333……1故至少有333+1=334人游的地方相同。
Look at the diagram. It something of home computer used by a group of young people. We asked thirty young people between fourteen and eighteen. We asked them how much they usually spent on their computers in a week, but we were most interested in they used their computers for. The usual time spent on a computer in a week was about twelve hours, with user about thirty-two hours, and the lowest user only five hours. All the children said they usually used computers . Fourteen children told us they did some word processing (文字处理) . Only two of them said computers helped with their lessons, and eight people told us they kept addresses and phone numbers on their computers or used as diaries. Only three people said they were learning to make computer programmes and nobody looked up databases(数据库). None of them used computers for any use. The results show that computer use is quite high among 14～18 year old. They also show quite clearly that computers by most young people as little more than game machines. The only other great uses are for word-processing and address lists. Though computers are common in the homes of young people, they have not yet become useful in everyday life.
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