主动语态怎么转变成被动语态

问题描述:

主动语态怎么转变成被动语态
多带一些例子

比如
i am doing my home work - am doing
my home work is done by me - is done
宾 + BE + 过去分词 + (BY 主语)有时会省略如:
my work is done.