MrKeller ______ forty cigarettes a day until he gave it up

Work hard, _______ you won’t do well in the exam.

So involved with computers ____ that the leaders at the summer computer camps often had to force them to break for sports．

Listen! Is it Linda singing in the next room –No, it __________ be her. She is still in Shanghai.

Not only __________do the work, but __________finishit on time.