Only when class began _______that he had left his book at home.
He is the only one of the students who _____ a winner of scholarship for three years.
Jim was very happy yesterday because he_____ the book that he wanted.
This is one of the problems_____ at the meeting at present.
I can’t go out with these clothes_____
The best way to prevent the air polluting _____ , but the sky is still not clear.