I don't know what I can say?和I don't know what can I say?有什么区别

Question

如题所述

Answer 1

宾语从句中从句是要使用陈述语气，不可疑问
所以
前句正确，后句错误

Answer 2

后面一个应该有语法错误！

Answer 3

I don't know what I can say?是对的
I don't know what can I say?是错的

Answer 4

我不知道能说什么 和 我不知道我能说什么呢？