被动语法

　　　　英语有两种语态,主动语态和被动语态.主动语态表示主语是谓语动作的执行者,或者是说动作是由主语完成.被动语态表示主语是谓语动作的承受者,或者是说动作不是由主语而是由其他人完成.一般说来,只有需要动作对象的及物动词才有被动语态,汉语往往用“被”、“受”、“给”等词来表示被动含义.
　　构成：
　　被动语态由“助动词be+动词的过去分词”构成.被动语态的时态变化只改变be的形式,过去分词部分不变.疑问句和否定句的变化形式也是如此.

　　另：含有情态动词的被动语态构成为“情态动词+be+P.P.”
　　 不定式的被动语态构成为“to be done”
　　1. English is spoken in many countries. (一般现在时)
　　2. Who was this article written by? (一般过去时)
　　3. An important meeting will be held in our school. (一般将来时
　　4. A new bridge is being built in the city. (现在进行时)
　　5. Everything has been done by him so far. (现在完成时)
　　6. Something must be done to protect wild animals. (情态动词
　　使用范围：
　　①不知道或不必指出动作的执行者
　　 These books are written for children. / We were asked to sing a song.
　　②强调动作的承受者,这时可带有by引起的短语.
　　 More trees must be planted by us next year
　　 A new machine was invented by Uncle Wang last month.
　　③当动作的执行者不是人时,多用被动语态
　　 The whole village was washed away by the flood.
　　④表示客观的说明常用“It’s +过去分词”句型.
　　 It is said that Lucy has gone abroad.
　　 这类句型有：
　　 It’s said that ….据说……
　　 It’s reported that….据报道
　　 It’s believed that….大家相信……

　　主动变被动4大步骤：
　　1、把原主动语态中的宾语变为被动语态中的主语,如为代词,宾格形式须变为主格形式.
　　2、把动词变为被动形式即be +过去分词,并注意其人称和数随主语的变化,而动词的时态则不变
　　3、原主动语态中的主语如需要则放在by后面变成by的宾语,如为代词,主格形式须变为宾格形式
　　 如不需要则可省略
　　4、其它成分（定语、状语）不变.
　　 Everybody likes this girl. ---- This girl is liked by everybody.
　　 He wrote a letter. ---- A letter was written by him.
　　被动语态注意事项：
　　1、不定式符号to在被动语态中不可省.在主动语态中,如果感官动词和使役动词后面的宾语补足语是动词,这个动词前往往不带to,但在被动语态中要带to.
　　I saw him climb up the hill.
　　He was seen to climb up the hill.
　　We heard him sing in his room just now.
　　He was heard to sing in his room just now.
　　2、主动语态中若有两个宾语,变为被动语态时,只将其中一个宾语变成主语,另一个宾语不变.主动结构中的间接宾语变为主语时,直接宾语仍然保留在谓语后面；直接宾语变为主语时,间接宾语前通常加上介词,这个介词是由与其搭配的动词决定,常为for或to .
　　1. We gave him some books.
　　 He was given some books (by us). 或 Some books were given to him (by us).
　　2. He gave me a book. A book was given to me by him.
　　3. He showed me a ticket. A ticket was shown to me by him.
　　4. My father bought me a new bike. A new bike was bought for me by my father.
　　5. A girl saw my wallet drop when she passed by.
　　 My wallet was seen to drop by a girl when she passed by.
　　6. The boss made the little boy do heavy work.
　　 The little boy was made to do heavy work by the boss.
　　3、一些动词短语用于被动语态时,动词短语应当看作一个整体,而不能丢掉其中的介词或副词.
　　We can’t laugh at him. He can’t be laughed at by us.
　　He listens to the radio every day. The radio is listened to by him every day.
　　The nurse is taking care of the sick man. The sick man is being taken care of by the nurse.
　　4、主动语态中如有复合宾语,变为被动语态时,只将复合宾语中的逻辑主语变成主语,其余部分不变
　　They asked him to take the medicine. He was asked to take the medicine.
　　We found him working in the fields. He was found working in the fields.牛津英语教研博客
　　不使用被动语态的几种情况：
　　1、不及物动词不能用于被动语态.如：appear, die, disappear, end, fail, happen, last, lie, remain, sit,
　　spread, stand, break out, come true, fall asleep, keep silence, lose heart, take place.例如：What was happened to him?(错误)
　　What happened to him? (正确)
　　2、系动词（包括感官动词）无被动语态（keep除外）,用主动形式表示被动意义.如：appear, be,
　　become, fall, feel, get, grow, look, remain, seem, smell, sound, stay, taste, turn.
　　The flower smells sweet.
　　The dish tastes delicious.
　　The cloth feels very soft.
　　It sounds good.
　　3、有些动词用主动形式表示被动意义.
　　This pen writes well.
　　4、want, need, require, worth等词后面可以用动名词的主动形式表示被动意义.例如：
　　The children need looking after.
　　The table wants cleaning

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