——Are these buses?—— .A. Yes, they’re.B. Yes, they are.C. Yes, they aren’t.
---Could you tell me when Mr Green _____ in Shanghai tomorrow? ---Sure. When he _____, I’ll tell you in time.
Gesang hasn’t seen _____ football game since last year.
_____ years ago, people first began to drink tea in China.
_____ is our duty _____ the environment.
_____ of our school is covered with trees and grass.