一、构成
被动语态由be＋过去分词构成，be随时态的变化而变化。 各种时态的被动语态
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.
二、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）接双宾语的动词的主动语态改为被动语态时有两种情况：
①把间接宾语改为被动语态的主语，直接宾语仍保留原位；
②把直接宾语改为主动语态的主语，此时，间接宾语前要加介词to或 for。
如： He gave the boy an apple．→The boy was given an apple．（或An apple was given
to the boy．不再是双宾结构）
Her father bought her a present．→She was bought a present by her father．（或A present was bought for her by her father．不再是双宾结构）
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。 这类词包括: look after, talk about, set up, put off, put up with, pay attention to, take care of 等。
例The meeting is to be put off till Friday.
三、 为何使用被动语态
1. 讲话者不知道动作的执行者或不必说出动作的执行者 (这时可省 by 短语)。
例 My bike was stolen last night.
2. 为了更好地安排句子。
例The well-known person got on the bus and was immediately recognized by people. （一个主语就够了）
四、 It is said that+从句及其他类似句型
一些表示“据说”或“相信”的动词如believe, consider, expect, report, say, suppose, think等可以用于句型“It＋be＋过去分词＋that从句”或“主语＋be＋过去分词＋to do sth.”。有：
It is said that… 据说,It is reported that…据报道，It is believed that…大家相信，It is hoped that…大家希望，It is well known that…众所周知，It is thought that…大家认为，It is suggested that…据建议。
例It is said that the boy has passed the national exam. （＝The boy is said to have passed the national exam. ）
五、主动表被动的特殊用法
1有些动词当它们和well, badly, easily等副词连用时，表示主语内在品质或性能，用主动表示被动，常见的有：write, read, clean, sell, wash, cook 等。
如： The cloth washes easily. The pen writes smoothly. 试比较：The door won't lock． （指门本身有毛病）
The door won't be locked． （指不会有人来锁门, 指“门没有锁”是人的原因）
2 某些连系动词：look, feel, smell, taste, sound, prove, appear等，用主动表示被动，常接形容词或名词作表语。
e.g. Your idea sounds reasonable. What he said proved to be correct.
3. 表示“发生、进行”的不及物动词和短语，如：happen, last, take place, break out, come out, come about, come true, run out, give out, turn out等以主动形式表示被动意义。
例 How do the newspapers come out? 这些报纸是如何引出来的呢？
The party turned out to be very successful.
His dream will come true sooner or later.
Our food supply has given out.
4． 在need，want，require, bear等词的后面，动名词用主动形式表示被动意义，其含义相当于动词不定式的被动形式。
例The house needs repairing（to be repaired）．这房子需要修理。
5． 形容词worth后面跟动名词的主动形式表示被动含义，但不能跟动词不定式；而worthy后面跟动词不定式的被动形式。
例The picture-book is well worth reading．（＝The picture-book is very worthy to be read．）
6. 不定式在某些形容词后作状语且和句子的主语（或宾语）构成逻辑上的动宾关系时此类形容词包括：difficult, comfortable, pleasant, fit, interesting, unfit, light, heavy,
dangerous, etc.
The sentence is easy to understand.
She found the problem hard to deal with.
7.不定式作名词的后置定语，和被修饰的名词有逻辑上的动宾关系，同时和该句主语构成逻辑上的主谓关系，不定式常用主动形式表被动含义：
She had only a cold room to live in.
I have a meeting to attend. She has many children to look after I gave him a cake to eat
8. 在be to do结构中的一些不定式:这种结构中的不定式通常应用主动表被动。
下列动词用不定式的主动形式表示被动意义:rent, blame, let Who is to blame for starting the fire?
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