21. Being a student, you should _______ your study instead of indulging yourself in computer games.
A. concentrate on B. rely on C. contribute to D. lead to
22．I am going to do all I can to remove the unpleasant_______ you have of me.
A. influence B. impression C. imagination D. conclusion
23. Joe is a good salesman; every month he sells a lot of products; everyone says he is a man who_______ .
A. gets the scoop
B. knows all the tricks of the trade.
C. has a good nose
D. gets the wrong end of the stick
