His funny hat made the students _____ in class.
—I think everyone must do his best to _______pollution.—If so, there will be a good future for people of tomorrow.A. keep B. stop C. stand
Could you tell me ______________ now?
China has became the third nation to send a person into space______________.
The air pollution is very serious,we should take___________to stop it.
I think it is __________for them to find the lost bag with the help of the police.