Cars do cause people some health problems, in fact far more serious _____ than computers do. 

Try hard to make what the teachers teach______,and you’ll all make good progress in your studies.

________ may have a chance to be successful if he tries his best.

------You ran into Mr. Li! How did that happen? ------Well, _______ of us was looking where we were going. We came around the corner at the same time.

 --- How many of you have solved the math problem?--- ________, the math problem is far too difficult for us to work out. .