主语补足语,（以下简称
主补）顾名思义,是对主语的补充,使得句子更加完整.请看下面的例句,并注意观察
谓语动词的语态：
1.He was called Jack.他曾被人称为杰克.Jack 是主补.
2.I was made angry.我被人气坏了.angry 是主补.
3.The book was put there.那本书曾被放在那里.there 是主补.
4.The book was thrown into a dustbin.那本书曾被扔进垃圾箱.into a dustben 是主补.
5.The boy was made to work hard 10 hours a day.那男孩曾被迫一天干10小时的重活.to work hard 是主补.
6.The water was kept boiling for ten minutes.水被保持沸腾10分钟.boiling 是主补.
7.The cup was found broken.茶杯被发现已打破了.broken 是主补.
可以看出,这些含有主补的句子都是
被动语态.也就是说,一个含有宾补的句子,如果转换成被动语态,那么原来的宾补就变成了主补.与宾补一样,主补也是不能丢掉的.
但是还有一类主补不是出现在被动语态的句子中,例如：
1.He left home a poor worker ten years ago and came back a rich business man.十年前他离家时是个穷工人,但回来时已是富有的生意人.a poor worker 和 a rich business man 均是主补.
2.His father died young.他的父亲死得早.young 是主补.
这种主补在语法界有争议,有的语法学家把这样的句子称为“双重谓语句”,这里就不多讲了.