—Hurry up! The bus is coming.—Wait a minute. Don’t cross the street the traffic lights are green.
---Where is the scientist ________ gave us the talk yesterday? ---He has gone back to Qinghua University.
The letter _______ I received from him yesterday is very important.
---Does the teacher know everybody _______ planted the trees?· ---Yes, he does.
I don’t know if he tomorrow. If he , I’ll meet him.
We won’t put off our plan __________ it snows heavily tomorrow.