１　John repaired the computer yesterday.
　　
　　２　The computer was repaired by John yesterday.

二　什么时候需要使用被动语态

1) 不知道动作的执行者时
　 Printing was introduced into Europe from China.
　 Modern education was introduced into China from Europe.

2) 当不必要提出动作的执行者时
　 His son was born in 1990.
　 The bridge was built in 1998.

3) 当强调或侧重动作的承受者时
　 The cute boy is liked by everybody in that room.
　 This job was done by that boy yesterday.

三　被动语态的构成

A 　被动语态的基本构成是：be +　过去分词。

B 　在把主动语态变成被动语态时，首先要找到主动语态里的主语，动词，宾语，在变成被动语态时，主语成了宾
　　语，动词成了be done, 宾语成了主语；其他句子成分不变。

　
主动语态：
Tom repairs computers in that shop everyday.
主语 　动词 　　宾语 　　　　　　状语

被动语态：
Computers 　are repaired 　by Tom 　　in that shop everyday.
主语 　　　 　　动词 　　 　介词的宾语 　　状语


Ｃ　下面是各种时态和情态动词的被动语态的构成和例句:

No	时态	被动语态构成	例子
1	一般现在时	am/is/are done	They usually design bridges. Bridges are usually designed by them.   She cleans the corridor everyday. The corridor is cleaned by her everyday
2	一般过去时	was/were done	The boy saw the accident yesterday. The accident was seen by the boy yesterday.   He broke the door last Sunday. The door was broken by him last Sunday.
3	一般将来时	will/be going to be done	Fred will plan the party tomorrow. The party will be planned by Fred tomorrow.   She is going to repair the car next week. The car is going to be repaired by her next week.
4	过去将来时	would be done	He said that he would plan the party next week. He said that the party would be planned by him next week.   He told me that he would fix the lock after lunch. He told me that the lock would be fixed by him after lunch.
5	现在进行时	am/is/are being done	He is cutting the tree now.  The tree is being cut by him now.    She is drawing a picture at the moment.  A picture is being drawn by her at the moment.
6	过去进行时	was/were being done	His mum was washing her clothes at 6pm last night.  Her clothes were being washed by her mum at 6pm last night.    They were repairing the car at 2pm yesterday.  The car was being repaired by them at 2pm yesterday.
7	现在完成时	has/have been done	David has fixed the machine.  The machine has been fixed by David.    The boys have kept the interesting book for two weeks.  The interesting book has been kept by the boys for two weeks.
8	过去完成时	had been done	He told me that he had written the report.  He told me that the report had been written by him.    That company had made 200 computers by the end of last week.  200 computers had been made by that company by the end of last year.
9	情态动词	情态动词+ be done	He can fix the computer. The computer can be fixed by him.   He could fix the computer yesterday. The computer could be fixed by him yesterday.   Students may use the computers here. The computers may be used by students here.   Students might use the computers here last week. The computers might be used by students here last week.   You must water the flower now. The flower must be watered by you now.   You should water the flower now. The flower should be watered by you now.   You ought to water the flower now. The flower ought to be watered by you now.   You have to water the flower now. The flower has to be watered by you now.