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问题 单项选择题

下列因素中哪些与数据库系统的运行效率有关　　Ⅰ功能是否齐全　　 Ⅱ．容错纠错能力　　Ⅲ．数据库设计是否合理　 　Ⅳ．程序可读性　　Ⅴ．算法　　 Ⅵ．编程技巧

A．Ⅰ，Ⅱ，Ⅲ和Ⅴ

B．Ⅰ，Ⅳ，Ⅴ和Ⅵ

C．Ⅱ，Ⅲ，Ⅴ和Ⅵ

D．都是

答案

参考答案：C

解析：可编程中断控制器8259A(8259A Programmable Interrupt Controller-PIC)用于管理和控制80×86的外部中断请求，实现优先级判决，提供中断向量码，屏蔽中断输入等。

单项选择题

电子或离子移动产生的电流称为（）

A.直流电流

B.交流电流

C.传导电流

D.位移电流

E.低频电流
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单项选择题

There is virtually no limit to how one can serve 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 (1) (VSO) for young people before they take up full-time employment, (2) there are opportunities for overseas service for (3) technicians in developing countries. Some people, (4) those who retire early, (5) their technical and business skills in countries (6) 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 experience; they must be joined with commitment to the (15) , not business efficiency. Because salaries are (16) or non-existent many voluntary bodies offer modest expense. 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.

18（）

A.before

B.on

C.in

D.at
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