—I'm going to the USA. —How long you there?A. are; staying B. are; stayed C. have; stayed D. did; stay
The pregnant woman always sits in the nonsmoking area of restaurants to reduce her exposure ________ smoke.
My visit to your school is really an unforgettable experience, ________ I will treasure for ever.
________ giving a general introduction to computers, the course also provides practical operation.
That coat fits me, but I can't afford to buy ________. I have to choose ________ that is cheap enough for me.
Difficult conditions will sometimes ________ a man's best qualities.