英语被动语句使用法

http://zhidao.baidu.com/question/16960696.html?si=5

一. 何时使用被动语态

1. 不知道谁是动作的执行者或没有必要

如：Paper is made from wood.

The house is quite old. It was built in 1950.

He was wounded in the fight.

2. 需要强调动作的承受者时

如：Calwlator can't be used in the maths exam.

Books and newspapers in the reading room mustn't be taken away.

He was awarded first prize in that contest.

3为了使语气婉转，避免提及自己或对方而使用被动语态，或由于修饰的需要，使用被动语态，使句子得以更好的安排。

如：The construction of the new lab must be completed by the end of next month.

Electricity is used to run machines.

二. 被动语态的构成

1. be+done 可以是被动语态，也可以是系表结构形式。被动语态中，done可以带by短语，而系表结构中done相当于adj. 不带 by短语。

如：The question is settled. (系表结构)

Such questions are settled by us. (被动语态)

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