第八章 被动语态
被动语态表示主语是动作的承受者。只有及物动词才能有被动语态。 1．
被动语态的构成
由 “be+过去分词”构成。以动词ask为例，将几种常用时态的被动形式列表如下： 一般现在时 现在进行时 am/is/are am/is/are asked 一般过去时 过去进行时 was/were asked 2．
现在完成时 一般将来时 have/has shall/will be being asked been asked asked 过去完成时 过去将来时 had been should/would be asked was/were being asked asked 怎样把主动语态变成被动语态
基本方法：用原宾语作被动句的主语；把原来的主动动词变成被动形式，要保持原时态；原主语变成by的宾语。
（1） 单宾语结构。如：
We all like music. → Music is liked by us all.
(2)双宾语结构。即可以用间接宾语（人）作主语，也可以用直接宾语（物）作主语。剩下的宾语仍留在原来位置上。如：
We gave him some books. → He was given some books. → Some books were given (to) him. (3) 复合宾语结构
含复合宾语的句子变被动语态时应以宾语作主语，宾语补足语仍留在原来的位置上，转化为主语补足语。如： They found the house empty. → The house was found empty. (4)含情态动词的句子
其被动语态形式是“情态动词+ be +过去分词”。如： We must work out a plan. → A plan must be worked out.
(5) 含多词动词的句子。 变成被动语态时，多词动词要保持完整性，即不能丢掉其中的副词或介词。如： We should take good care of the children. → The children should be taken good care of. （6）主动语态为祈使句时。如： Do it at once.
→ Let it be done at once. 3.被动语态的使用场合
（1） 强调动作的承受者时。如：
The classroom is cleaned every day. 教室每天被打扫。 （2） 不知道动作者是谁，或虽知道但不愿说出时。如： This letter has been opened. 信被打开了。 (3) 主语部分太长时。如：
This machine was invented by a student who had just graduated from Beijing University. 这台机器由一名刚从北京大学毕业的学生所发明。
(4) 动作者为非特定的对象，没有说出的必要时。如： English is spoken in Australia. 澳大利亚讲英语。 （5）用于某些固定句型中。如：
It is said that…, It is hoped that…, It is well known that…, It is believed that, It must be pointed out that…, It is reported that…, It has been decided that…, It is thought that.., It is suggested that…等。
被动语态
