----When did the concert ? ---Well, two or three years ago?
The war made ______ impossible for the scientist to go on with his research.
He often takes this road to avoid ______ the troublesome boy.
As is known to most of us, Maodun was born in _______is now called Wuzhen.
Please speak in a _______ , or the teacher will hear what you say.
--Excuse me, I don't think you can smoke here. ---Really sorry. I ______ this is a non-smoking room.