I apologize for ...
the bad behaviour of my sister.
I’m sorry for the trouble I caused.
I’m sorry, but I can’t make it to the meeting.
I promise it won’t happen again.
I’m sorry to say that ...
I've lost the book you gave me last weekend.
I hope you won’t mind me saying that ...
the place you’d recommended to us wasn’tas nice as we’d expected.
the bike I bought from you last weekisn't any good.