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问题 选择题

光线A射到平面镜的O点处，反射光线在墙上出现一个光斑Q，如图所示．保持平面镜和入射点O的位置不变，慢慢减小入射角，则墙上光斑Q的位置会（　　）

A．向下移动

B．向上移动

C．保持不变

D．无法确定

答案

过入射点O作出法线，保持平面镜和入射点O的位置不变，慢慢减小入射角，根据反射角等于入射角，作出反射角，则墙上光斑Q的位置会向上移动，（红色光线），如图所示：

选择题

 

27. More and more Chinese women are having difficulty ______ Mr. Right or are choosing the single life.

A．to find

B．finding

C．found

D．in being found
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单项选择题

There is virtually no limit to how one can serve (1) community interests, from spending a few hours a week with some charitable organization to practically full-time work for a social agency. Just as there are opportunities for voluntary service (2) (VSO) for young people before they (3) full-time employment, so there are opportunities for overseas service for (4) technicians in developing countries. Some people, (5) those who retire early, (6) their technical and business skills in countries where there is a special need.
So in considering voluntary or (7) community service there are more opportunities than there (8) were when one first began work. Most voluntary organizations have only a small full-time (9) , and depend very much on volunteers and part-timers. This means that working relationships are different from those in commercial organizations, and values may be different. (10) some ways they may seem more casual and less efficient, but one should not (11) them by commercial criteria. The people who work with them do so for different reasons and with different (12) , both personal and (13) One should not join them (14) to arm them with professional expertise; they must be joined with commitment to the (15) , not business efficiency. Because salaries are (16) or non- existent many voluntary bodies offer modest expenses. But many retired people take part in community service for (17) , simply because they enjoy the work.
Many community activities possible. (18) retirement were also possible during one’s working life but they are to be undertaken (19) seriously for that. Retired people who are just looking for something different or unusual to do should not consider (20) community service.

A．quantity

B．qualifying

C．quality

D．qualified
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