(单选题)7: 变压器漏感使整流电路出现换相重叠角，整流输出电压平均值（）。 A: 升高 B: 降低 C: 不变 D: 不确定 ...

(单选题)1: 正弦电路中功率因数定义（）和（）的比值。 A: 有功功率，无功功率 B: 有功功率，视在功率 C: 无功功功率，视在功率 D: 无功功率，有功功率 ...

(判断题)17: 变压器漏感使整流电路换相时电网电流出现缺口，成为干扰源。 A: 错误 B: 正确 ...

(多选题)11: 三相桥式不可控整流电路交流侧谐波组成有如下规律： A: 谐波次数为6k±1次，k∈Z+ B: 谐波次数越高，谐波幅值越小 C: 谐波次数为奇次 D: 谐波次数越高，谐波幅值越大 ...

(单选题)5: 升压斩波电路输出电压（）电源电压。 A: 高于 B: 低于 C: 等于 D: 不确定 ...

(单选题)13: My wallet is nowhere to be found. I ________ in the store. A: must drop it B: must have dropped it C: should have dropped it D: ought to have dropped it ...

(单选题)1: We had warned him __ the danger but he turned a deaf ear to our warning. A: at B: of C: / D: with ...

(单选题)8: "I have never seen a Beijing policeman." "You_____ one. You've been in Beijing a week already." A: must see B: will have seen C: would have seen D: must have seen ...

(单选题)21: I ____________to the cinema a lot, but I never get the time now. A: am used to going B: used to go C: am used to go D: used to going ...

(单选题)15: — I think he is a good lecturer. — ____________________ A: Sorry, it doesn’t matter. B: So do I. C: Yes. It’s a good idea. D: I don’t mind. ...