Sorry I am late. I missed the bus.
I apologise. It was my mistake.
I apologise for talking to you like that.
I am afraid, I can't come on Sunday.
I am sorry it is wrong number.
I am sorry I am late.
I could not return the book yesterday. I am so sorry.
It doesn't matter, but don't make it a habit.
I am sorry. I forgot to post the letter.
No problem. You can post it tomorrow.
I am sorry. I have broken the cup.
That is okay. It sometimes happens like that.
I am sorry. I have disturbed you.
No, not at all.
I am terribly sorry. This is all entirely my fault.
Okay, it doesn't matter, but don't let it happen again.