He was not the man_ he was before.空格中填that,为什么不填what

Question

He was not the man_ he was before.空格中填that,为什么不填what

Answer 1

这是一个定语从句,that是关系代词修饰theman,既可以指人也可以指物,what只能引导名词性从句
hat引导名词性从句时,不在从句充当任何的句子成分,也没有意思,只起到引导作用.也就是说在that引导的名词性从句中,如果把that去掉,从句是一个成分和意思都完整的句子.（注;that在引导主语从句,表语从句,同位语从句时是不能省略的；在宾语从句中一般可以省略,具体什么情况不能省略的你百度一下就知道了）
what引导名词性从句时,在从句中充当主语、宾语或表语,意思为“什么,.的（东西/事情）”.如果把what去掉,从句成分和意思都不完整.what引导名词性从句不能省略.
1.What he wants is a book.他想要的是一本书.
（what 引导主语从句What he wants,在从句中作做动词wants的宾语,如果把what去掉,从句剩下的he wants 意思和成分不完整了）
2.The result is that we won the game.众所周知,光是沿直线运行.
（that 引导表语从句that we won the game,只起连接作用,如果把that去掉,从句剩下的 部分we won the game意思和成分都完整）
3.This is what we are looking for.这是我们正在寻找的东西.
（what 引导表语从句what we are looking for,它在从句中作looking for 的宾语,如果把what去掉,从句剩下的就是 we are looking for,意思不完整,同时也缺少宾语.）
4.What excited us most was that he passed the exam.使我们感到兴奋的是,他考试通过了.
（what 引导主语从句What excited us most ,在从句中作主语,t如果把what去掉,从句剩下的就是excited us most ,从句缺少主语并且意思也不完整.that引导表语从句that he passed the exam,它在从句中不作成分）
5.The trouble is that they say doesn’t agree with what they do.问题是他们说的与他们做的不一致.
（that 引导表语从句 that they say doesn’t agree with what they do,不作成分,what 引导宾语从句what they do,而且what 在宾语从句中作do 的宾语.）