Have you ever done hitchhiking?
yes, I have.
No, I haven't. I have never done it.
No, I haven't. I haven't done it yet.
Have you ever climbed a mountain?
yes, I have. I've already climbed it. I went to..
No, I haven't. I haven't climbed a mountain yet.
Have you ever been to a costume party?
yes, I have.
No, I haven't. I haven't been to a costume party yet.