问题 问答题 简答题

换向绕组的作用是什么,装在什么位置,流过补偿绕组的电流是什么电流。电流方向如何。

答案

参考答案:换向绕组的作用是帮助直流电机良好换向,一般装在主磁极之间,与电枢绕组串联;直流电机只有在容量较大时才加装补偿绕组,目的是帮助换向极绕组进一步补偿直流电机良好换向,装在主磁极上;补偿绕组一般与电枢绕组串联,则流过补偿绕组的电流为电枢电流;电流方向为补偿换向的方向。

阅读理解

You may open your electronic mail and find information about how to buy medicine, cheap airline tickets, books and, of course, computers and computer products.There may also be offers for investment deals, bank loans and special holidays.However, to many computer users, this use of electronic spare to sell products has become a major problem as it makes computer communication more difficult.

Many companies who want to send a great deal of advertising might use the services of a “spammer.” A spammer is a person or company that uses computers to send out millions of copies of the same sales information.Spammers find e-mail addresses from websites, news groups and “chat rooms” where people send messages to each other.Most spare is sent by companies who are trying to get you to buy their products.Some of these are honest companies that offer good products or services for a fair price.These companies can offer their products at a cheaper price than you might find in a store.However, much of the spam on the Internet is sent by criminals who are trying to sell products that do not exist or offer services they will not provide.They are only interested in stealing your money.When you answer their spam you find you are expected to send them money and receive a gift.One country in Africa has become famous for the number of criminals who try every known trick to separate people from their money.

小题1:What does the  underlined word “spam” in the paragraph probably refer to ?

A.Unwanted electronic information that reaches computer users.

B.Computer virus that causes computer communication difficulties.

C.Advertisements sent out by companies who want to sell their products.

D.Companies that send out millions of copies of the same sales information.小题2:.Which of the following is TRUE according to the text?

A.Companies who want to send a great deal of advertising are referred to as spammers.

B.Spammers are people who collect e-mail addresses from websites, newsgroups and “chat rooms”.

C.Either individuals or organizations can be regarded as spammers if they send out spam.

D.Spammers are people who receive spam on their computers.小题3:Which is the possible suggestion from the writer concerning spam ?

A.Spain is very helpful in providing you with useful information about product sales.

B.Spam helps companies to sell more of their products so it should be valued by people.

C.Spam is sent out by those who want to separate you from your money.

D.Look out for any spam that reaches your computer

单项选择题