I don't know what's the matter. 是对的,what在句中作主语。
祝你进步!
我们以前学语法的时候,这句话的What是做表语的.
I don't know what the matter was.是对的.
按语法规则来说,I don't know what the matter was是对的
可是在与老外对话时,一般都说I don't know what's the matter.
I don't know what the matter was.
宾语从句中的疑问句是要用正常语序,而不是倒装,例如I don't know what this is. 主语从句中也一样,所以what this is is unclear在语法上才是正确的。不过话说回来,这样似乎并不是地道的英语,可能说It is unclear what this is 或者I don't know what this is会更好 。
what前有停顿就是前一个 连起来后面的对