Indicates that the speaker is confused or requests information to be repeated; come again?, say again?, I beg your pardon?; see also Thesaurus:say again
Indicates the speaker's commiseration.
Indicates the speaker's apology.
Don't let it bother you; put it out of your mind.
I don't want to continue with this conversation (usually used in frustration or anger).
It doesn't matter.
A conventional reply to an expression of gratitude.
Absolutely not; I forbid it or it is impossible.