"Mary, turn off the water_________you are brushing your teeth. " "Sorry, I'll do it at once. "A. until B. while C. during
You ____ swim here. It is said that sharks (鲨鱼) have been seen.
— I hope you can ____ and see us next time you come to Shanghai. — Sure, I will.
Playing computer games ____ the boy so much time that he doesn’t have enough time to study.
As students, ____, we should study hard to be well prepared for the future.
The maths problem was so difficult that none of us could ____.