如何正确的使用被动语态

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)
The composition is well written. (系表结构)
The composition is written with great care . (被动语态)
The job was well done. (系表结构)
The job was well done by a skilled worker. (被动语态)
2. 许多verbs(broken, interested, shut, worried), 既可以用做adj.也可以在被动语态结构中做过去分词。句中如果有by，通常是被动语态。
如：I was worried abeutyou all night. (表状态)