Look, what have they done? —Sorry. I think ifI __________ another chance, I’ll do it better.

下列各句中，表达得体的一句是

Robert is indeed a wise man.— Oh, yes. How I have regretted ________ his advice![ ]

We have every reason to believe that our business hasshown a(n) ____ to improve.

I intend to buy a present for my mother’s birthday, ________ at the proper price but of great value.