A: I'm sorry I forgot to bring the key of my room.

不好意思，我忘记带房间的钥匙了。

B: That's all right.

没关系。

A: I'm sorry I'm late. The train was delayed.

对不起，我迟到了。火车晚点。

B: That's all right. It can't be helped.

没关系，这是没有办法的事。