1．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）

2．主动变被动的基本方法：（说起来容易，掌握起来需要用心！）

（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. joozone.com