The question that puzzled them is ____ they can get rid of the air pollution in the area.

Why _______ you be so stubborn You should think over my advice on this matter.

The old couple will never _____ the loss of their son

__enough money, the young man was unable to buy his girlfriend expensive jewelry.

12MrWhite works with an import and export company, but he ______ for this industrial fair, since he is on leave