被动语态的概念

　　主动语态：主语是谓语动词动作的执行者；被动语态：主语是谓语动词动作的承受者。
变化方法：主动语态的主语（动作执行者）变成被动语态的宾语（用介词by引导）；主动语态的宾语（动作承受者）变成被动语态的主语；谓语动词由主动式(do)变成被动式（be +done）。如：We speak English in China.→English is spoken by us in China.

　　被动语态用法

① 不知道谁是动作的执行者(即不知道谁做)时用被动语态,省略by短语。如：A man was killed in the accident.(一个人死于事故)/ This window was broken yesterday.(这扇窗子是昨天被打破的)
②不说或者众所周知是谁做时,用被动语态,省略by短语。如：Rice is also grown in this place.(这个地方也种水稻)/ A railroad will be built here in three years.(三年之后这里将要修建一条铁路)
③强调动作的承受者,句尾加by短语。如：It was written by Lu Xun.(它(书)是鲁迅写的)/ A pet dog is never killed by its owner.(宠物狗是不会被主人宰杀的)

　　被动形式表示主动意义

被动形式表示主动意义主要有下面两个考点需要同学们注意：
1）一些固定词组，它们的被动形式通常表示主动意义。
例如be concerned with/ about（关心），be dressed in（穿着）. be hidden（躲藏起来），be located（位于），be lost in（陷入，迷路），be seated（就座）等。大家看下面例句：
That’s fine，as far as we’re concerned. 就我们而言，那样挺好。
After everyone was seated，the teacher began to read the result.
同学们就座后，老师开始读考试结果。
2）还有一些动词构成的被动形式也表示主动意义。
这类词组有: be used to（习惯于），be born（出生），be determined（决心，决定），be prepared（准备）等。

　　被动语态例句

1The floor was swept.地板打扫了。
2The letter was written by him.这封信是他写的。
3The glass was broken by the boy.杯子被那个男孩打破了。
4English is spoken by many people in the world.
世界上许多人说英语。
5Knives are used for cutting things.
刀用来切东西。
　　特殊情况的被动语态：
1.带双宾语的被动语态：
动词+ sb(间宾)+sth(直宾)
口诀：如遇双宾语，一般变间宾，若把直宾变，to/for间宾连。
1).give/pass/show与介词to搭配。
give sb sth 被动 :sb +be given sth或sth +be given +to sb.
e.g.He gave me a book
Iwas givena book by him.
A bookwas given tome by him.
2).buy/make/cook与介词for搭配。
buy sb sth被动:sb +be bought + sth或sth +be bought +for sb
e.g.My mother made me a cake.
I was made a cake by my mother
A cake was made for me by my mother.
2.带省to的不定式作宾补的被动语态：动词+ sb + do sth.
口诀：感使动词真叫怪，to来to去记心怀，主动语态to离去被动语态to回来。
动词：make/ let/have/see/hear/feel/watch
make sb do sth被动:sb + be +made +to do sth
e.g.The boss made the workers work all day
The workers was made to work all day by the boss.
3.see/hear/notice/keep +sb +doing sth句型中变被动语态时doing不变。
e.g.I heard Tom singing just now
Tom was heard singing by me just now.
4.以动词短语作谓语的主动语态变被动语态时，不可丢掉后面的介词或副词。
e.g.We should take care of the old.
The old should be taken care of.

2被动语态的构成形式

1.被动语态的基本时态变化
被动语态通常为十种时态的被动形式, 被动语态由be 过去分词构成，be随时态的变化而变化。以do为例，各种时态的被动语态形式为：
1)am/is/are done (过去分词)一般现在时
例Visitors are requested not to touch the exhibits.
2)has/have been done 现在完成时
例All the preparations for the task have been completed, and we're ready to start.
3)am/is/are being done 现在进行时
例A new cinema is being built here.
4)was/were done 一般过去时
例I was given ten minutes to decide whether I should reject the offer.
5)had been done 过去完成时
例 By the end of last year, another new gymnasium had been completed in Beijing.
6)was/were being done 过去进行时
例A meeting was being held when I was there.
7)shall/will be done 一般将来时
例Hundreds of jobs will be lost if the factory closes.
8)should/would be done 过去将来时
例The news would be sent to the soldier's mother as soon as it arrived.
9)shall/will have been done 将来完成时(少用)
例The project will have been completed before July.
2.被动语态的特殊结构形式
1)带情态动词的被动结构。其形式为：情态动词 be 过去分词。
例The baby should be taken good care of by the baby-sitter.
2)有些动词可以有两个宾语，在用于被动结构时，可以把主动结构中的一个宾语变为主语，另一宾语仍然保留在谓语后面。通常变为主语的是间接宾语。
例His mother gave him a present for his birthday.可改为 He was given a present by his mother for his birthday.
3)当“动词 宾语 宾语补足语”结构变为被动语态时，将宾语变为被动结构中的主语，其余不动。
例Someone caught the boy smoking a cigarette.可改为The boy was caught smoking a cigarette.
4)在使役动词have, make, get以及感官动词see, watch, notice, hear, feel, observe等后面不定式作宾语补语时，在主动结构中不定式to要省略，但变为被动结构时，要加to。
例Someone saw a stranger walk into the building.可改为A stranger was seen to walk into the building.
5)有些相当于及物动词的动词词组，如“动词 介词”，“动词 副词”等，也可以用于被动结构，但要把它们看作一个整体，不能分开。其中的介词或副词也不能省略。
例The meeting is to be put off till Friday.
3.非谓语动词的被动语态
v.ing 形式及不定式 to do 也有被动语态(一般时态和完成时态)。
例I don't like being laughed at in the public.