The OPEC has recently cut backproduction and the price of oil has been ______ to $90 a barrel .

ept looking at the pretty girl, wondering whether he_________ her somewhere.

If we ___________some measures, we might have prevented the environmental pollution．

Could you tell me __________—Certainly. In half an hour.

Would you like to order the two robots— Yes， one is to help me with my homework， and ____ is for my mother to do housework.