“what i said is true”这里的what能否换成that?为何?

“what i said is true”这里的what能否换成that?为何? I know what you said is true. I think what you said is true what you say is true.中的主语what you say 可换成what you said吗 that is what i say.这里的what是引导的表语从句吗?能换成which吗. I am sure that what he said is true.是什么从句 i believe what he said is true?A.that B.不填 为什么不能选择A? what i said that is true!加标题一起翻译 谢谢 I am sure___you said is true.答案是what,为什么不是that What you said yesterday s___ me.Is that true? what you say is quite true.中的what等于that which.若换成that which 为什么I think that it is true是附属简单分句,而What you have said is tru