如题所述
正常情况下的宾语变成主语时，可以认为是被动语态。
如： He wrote a letter yesterday。 a letter是主动语态的宾语。
A letter was written (by him) yesterday. a letter成为主语，它不会是自己写的，所以是被动语态。
They have cut down the tree. the tree是宾语。
The tree has been cut down (by them). the tree成为主语，它不会自己砍的，所以是被动语态。
如： He wrote a letter yesterday。 a letter是主动语态的宾语。
A letter was written (by him) yesterday. a letter成为主语，它不会是自己写的，所以是被动语态。
They have cut down the tree. the tree是宾语。
The tree has been cut down (by them). the tree成为主语，它不会自己砍的，所以是被动语态。
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第1个回答 2011-11-20
看看是否有被动语态的词语Be动词再加上done，要是英语句子看看是什么时态，
进行时态的being done
过去式was/were done
完成式have/had been done
进行时态的being done
过去式was/were done
完成式have/had been done
第2个回答 2011-11-21
is am are were was+过去分词
或过去分词作状语
或过去分词作状语
