这题怎么选 Water,which seems so simple and common,is what makes life possible.

题目

这题怎么选 Water,which seems so simple and common,is what makes life possible.
Water,which seems so simple and common,is ___ makes life possible.
A what B which
为什么不选B which也可以做主语啊?

答案

中间的那部分which seems so simple and common是个插入语,可以省略,整个句子就是Water is _what___makes life possible.
what在此处作主语.
"is"后面是个表语从句,虽然which可以引导表语从句,但是不能充当从句的主语,通常充当定语和表语,表示“其中哪一个”
所以此处选择答案A what.