I just want to know. Now I know who you mean. Your brother looks like you. He lives on the fifth floor.
Does anyone live with my brother?
Yes.
Who lives with my brother?
There is a girl who lives with your brother.
Who is she? Please tell me about her.
I cannot tell you who she is. Why don't you ask your brother? I want to know who she is. I wonder who she is.
I am sorry I cannot tell you who she is. Your brother will tell you if he wants to.
I am sure you know but just don't want to tell me. I do not have to tell you. I do not think I should tell you.
But you could tell me if you wanted to. You must tell me.