Is ( )you told me really true?该句括号中填that 还是what?为什么?

that
你抓主干，
Is that really true?这句对的
如果你用what就是
is what really true?
你自己看应该选啥。

what
整个what you told me是作为主语的。而that自己就可以做主语了。

what
是what引导的主语从句

what
前面与后面都缺少成分，只有what可以代表2个成分

答案：what
what引导主语从句,what在主语从句中做宾语.
方法：把这句话变成陈述句.()you told me is really true.
这样更容易分析句子结构,就能找出答案.

Is (what )you told me really true.
还原为陈述状态：what you told me is really true.
这里what引导主语从句，可以作为成分，that不可以。