问题 单项选择题 案例分析题

某电网规划建设一座220kV变电所,安装两台主变,三侧电压为220/110/10kV。220kV、110kV为双母线接线,10kV为单母线分段接线。220kV出线4回,10kV电缆出线16回,每回长2km。110kV出线无电源。电气主接线如下图所示,请回答下列问题。

该变电所10kV侧采用了YN,d接线的三相接地变压器,且中性点经电阻接地,请问下列哪项接地变压器容量选择要求是正确的?为什么?()(注:SN为接地变压器额定容量;PR为接地电阻额定容量)

A.

B.Sn≤PR

C.Sn≥PR

D.Sn≥

答案

参考答案:C

阅读理解

If you have a problem with speaking, you can do several things. Listen to English as much as possible. You can learn a poem(诗) or a song by heart. You can also learn more dialogues(对话). And practice speaking with your friends as much as you can.

Many people find it difficult to listen to English. The answer is to listen as much as you can. However, don’t do too much at one time. It is better to practice listening for five minutes every day. Don’t sit down and listen for an hour at a time. That’s too much! Do choose listening passages that are interesting and not too difficult. Choose(选择) tapes(磁带) on which the people speak clearly and not too fast. Take it easy, at first. Success with simple tapes at the beginning is the answer. Later on you can practice with tapes that are more difficult.

Finally, how can you learn to write well? How do you use little words like in, on, of and for? There are two answers to this. First, do some study with new words. Keep a list of verbs like look for, look after and so on. Second, read as much English as possible. There are many things that can’t be learnt. You must see them in books many times. Then you’ll be able to use them correctly(正确地) yourself. So, in order to write well, you must first learn to read much.

小题1:This passage is about English ______ .

A.spelling, listening, grammar and reading

B.listening, speaking, reading and writing

C.taking exams, pronunciation, reading and writing

D.pronunciation, reading, listening and writing小题2:If you ______ , you can speak well.

A.learn more dialogues

B.learn a poem or a song by heart

C.practice speaking with your friends as much as you can

D.all above小题3:Which of the following is right according to the passage?

A.It’s better to listen to English for a long time every day.

B.At the beginning, you’d better choose the tapes on which the people speak quickly.

C.At first you should begin with simple tapes for listening.

D.Few people think it hard to listen to English.小题4:Which of the following ways can help you to improve(提高) your written English? 

A. Buy books of writing practice.        B. Read as much as possible.

C. Do some study with new words.      D. Both B and C.

小题5:Which of the following is not right according to the passage?

A.Many people find it difficult to listen to English.

B.Sit down and listen for an hour at a time.

C.Learn a poem or a song by heart can improve your speaking.

D.To improve speaking, you can practice speaking with your friends as much as you can.

单项选择题