Translation of "Referring" in Chinese

Who are you referring to?

你是指誰？

Are you referring to me?

你在说我吗？

Which one are you referring to?

你指的是哪个？

- I don't know what you're referring to.
- I don't know what you are referring to.

我不知道你指的是什么。

- Whom are you speaking of?
- Who are you referring to?
- Who are you talking about?

你是指誰？