she knows that what children learn from books is useless中为什么that后可以跟what
问题描述：
she knows that what children learn from books is useless中为什么that后可以跟what
答
that是宾语从句的引导词,它后面接的是一个what引导的主语从句
答
这是一个从句 what是指孩子们从书上学到的东西
答
what children learn from books 是that的定语
she knows that is useless