问题 单项选择题

发电机在空载情况下运行,自动电压调节器投入,改变同步发电机转速,使频率变化为±3Hz,测定同步发电机端电压对频率的变化率并用与空载额定电压之比的百分率来表示,就会计算出励磁装置的()。

A.静差率

B.调差率

C.频率特性

D.超调量

答案

参考答案:C

填空题

根据首字母或中文完成句子。

1. At the museum, visitors are requested not to touch the e_______________.

2.The government yesterday ___________(宣布) to the media that they would create some new jobs.

3.The IT i___________ is playing an important role in the development of economy.

4.Though caught in a snowstorm, the pilot g _________ the plane to a safe landing.

5.Three fourths of the earth's s _________ is covered with water, our earth is an ocean planet.

6.I feel really happy to be e _________ in this famous university to teach advanced English.

7.He was too _____________ (没经验) for the job. He worked here no more than three days .

8.Many young soldiers helped to r ___________ people from the fire of the hotel. One of them was

killed and some were injured.

9.Some students in our class are worried about their p ___________ and want many people to like them.

10.He suddenly experienced a f ____________ of shame when his name was mentioned at the meeting.

11.My computer c ________ suddenly last night and all of my documents I was working on got lost.

12.The child was t __________ at the piano his parents sent to him on his birthday.

13.This machine is used to ___________ (监测) a patient's pulse.

14.The decision was c ________ by all the members.

15.He seems to be honest and trusted, but in r ________ he often tells lies.

16.He has an e __________ talent for music.

17.I think that we have many o __________ of meeting interesting people on the train when traveling.

18.Matter has three states . For example, water is ___________(液体).

19.A number of parents have v _______ concern about their children's safety.

20.She d ________ a talk on philosophy during her visit to her mother school.

单项选择题