"我不知道你在说什么"的英文怎样说?

I don't know what do you mean.
I didn't catch you very much.

直译为：
I don't know what you are saying（我不知道你现在在说什么）
I don't know what you said（这是我不知道你刚才说什么）
英译为：
I don't know what you mean(不能是I don't know what do you mean. 因为前面有I don't know后面应该为正常语序，上两句同理）
I can't understand you（我不明白你说什么）

I dont know what you are talking about
I dont know what you are saying

I don't know what you speak 绝对错。
I don't know what you say 绝对错

I don’t know what you’re talking about.

I don't know what you say

是say
speak后面加语言,如:speak Chinese

I don't know what you are talking about/saying
绝对正确