对不起：Excuse me

Sorry

I'm sorry

I'm so sorry

Please forgive me

I beg your pardon

没关系：It doesn't matter

That's OK

That's all right

Never mind

All Right

I'm all right

Don't mention it

Don't worry about that.

(这些“没关系”是针对“对不起”说的，还有一些“没关系”是针对“谢谢”说的，例如“Not at all，You're welcome!”等)