何时运用被动语态：
（1）强调动作的接受者：America was discovered by Columbus.
（2）不知谁是动作的执行者：You are wanted on the phone.
（3）作客观说明：It is said that the meeting has been put off. （经典句型）
主动变被动的基本方法：
（1）主动语态中的宾语变为被动语态的主语。
（2）谓语动词变为由“be + 过去分词”的形式，配合时态作相应变化。
（3）主动语态主语置于介词 by之后，如无必需，则省略。
（4）不及物动词没有被动语态。
现 在 do (does) →am / is / are + done
We keep the piano in the living-room.
→The piano is kept in the living-room.
过 去 did→was / were + done
They built the bridge in 1980.
→The bridge was built in 1980.
将 来 will/shall do → will/shall + be + done
He will read the book tomorrow.
→The book will be read tomorrow.
现在完成 have/has done → have/has + been + done
We have delivered the newspaper.
→The newspapers have been delivered (by us).
过去完成 had done → had been done
She had seen the film before she came here.
→The film had been seen before she came here.
将来完成 will/shall have done → will/shall have + been + done
By the end of this term we shall have finished 80 texts.
→By the end of this term 80 texts will have been finished.
现在进行 am/is/are doing → am/is/are + being + done
They are drawing the picture.
→The picture is being drawn by them.< /p>
过去进行 was/were doing → was/were + being + done
He was reviewing their lessons at this moment yesterday.
→Their lessons were being reviewed at this moment yesterday.
情态动词 may may
can can
must must
should do → should + be + done
ought to ought to
used to used to
You must write an article on the subject.
→An article must be written on the subject.
