Was it what she heard with her ears that really made her frightened?为什么要用WHAT和THAT用THAT和WHICH不行吗这是个强调句吗

Was it what she heard with her ears that really made her frightened?
为什么要用WHAT和THAT用THAT和WHICH不行吗
这是个强调句吗

是强调句的一般疑问句形式,what引导主语从句并且做heard的宾语因此不能用that

是强调句，what she heard 是主语从句，名词性的 不能用that ,而that made her frightened中的that 是强调句结构中的一部分不能用which，但是可以省略掉

WHAT做heard的宾语that做made主语