(判断题)15: 矩阵式变频电路能量只可以单相流动。 A: 错误 B: 正确 ...

(单选题)9: 将整流变压器的二次绕组移相（）度，可构成串联4重联结电路。 A: 15 B: 20 C: 30 D: 60 ...

(单选题)3: 单相交交变频电路改变变流电路的（），就可改变输出频率。 A: 频率 B: 相位 C: 电压 D: 控制角 ...

(单选题)16: "I must be going now.""Oh, it's still early, _____ you stay a bit longer?" A: will B: wouldn't C: won't D: can ...

(单选题)17: Every year thousands of lives _______ in road accidents because of careless driving. A: lose B: lost C: have lost D: are lost ...

(单选题)11: — Madam, do all the buses go downtown? — ____________________ A: Wow, you got the idea. B: No, never mind. C: Pretty well, I guess. D: Sorry, I’m new here. ...

(单选题)5: "Have a drink?" "No thanks, _______ ." A: I would not B: I would rather not C: I could not D: I do not ...

(单选题)25: It was decided to ________ the search when there was no hope of finding the missing girl alive. A: call off B: take up C: keep off D: ring up ...

(单选题)19: "Do I have to meet you at the station?" "It's up to you. You______ if you don't want to." A: needn't B: mustn't C: shouldn't D: wouldn't ...

(单选题)13: It was not until then that I came to know knowledge ____only from practice. A: had come B: came C: would come D: comes ...