问题 多项选择题

直流换流器准稳态模型基于的前提条件包括()。

A.换流母线电压是对称的正弦波且频率恒定

B.换流变压器三相平衡,并忽略其内电阻

C.平波电抗器电感极大,使得直流电流平直、无纹波

D.各桥阀以等相位间隔依次轮流触发

答案

参考答案:A, B, C, D

填空题

Good afternoon, everybody. I’m pleased to be here with you, graduates of 2007. I’m a (1) , and students often approach me with (2) . You see, we are living in a society of great changes. With the presence of (3) , the process of getting a job in today’s world has changed for (4) .
Well, how can you use new technologies to help you First, let’s look at how you (5) . The traditional method of hunting for a job in the past required first, doing research on jobs that were (6) , typically by looking in newspapers, periodicals and magazines, as well as TV ads, and (7) . Then you decided where and for what post you were going to apply, put your resume (8) in a stamped envelope, and waited anxiously for someone to (9) .
Well, today, maybe the job search and (10) are very much the same, but the tools used are much more advanced, and they (11) . In fact, technology has not so much changed the process as enhanced it. The benefit, both for (12) , is that this makes the search more open to people of (13) from all over the world. But as more people are involved, it becomes (14) for the applicant than it ever was before.
The (15) for the working world today is learning these new and (16) and combining them with the older methods people have been using for years. For example, (17) , you can research employment not just in your city, but also in your state, your country, and (18) . You can copy information from a web page and paste it into a Microsoft Word document that’s easy to (19) . In many ways, it’s easier now: Just type your job application, click, and (20) ; it gets there in an instant.

单项选择题