Question

一个英语语法问题

He is quite worn out from years of hard work.He is not the man___he was twenty years ago.为什么不填who?
正确答案这里填that啊，可是who为什么不行？

Answer 1

这涉及到一个英语的习惯和固定搭配问题。
我们先来看这个句子：China is not the country what is was be ten years ago.在这个句子中，china以前的模样，除了用what，我们确实想不出得用什么代替了，用that、who、which在这里明显不妥。
也就是说，无论是人还是物，在这里都要用what，没法解释的。只能记住。
这是个固定搭配：sth.was not the sth. what it .....+时间+ago

Answer 2

He is not what he was twenty years ago

He is not the man (that) he was twenty years ago
前面有the one ,the 只能用that 不用who

Answer 3

这是一句定语从句但是少表语
其实是He is not the man___he was （what）twenty years ago.