21. Eric was so foolish. He didn't even have ________ common sense to send for ______ doctor.

A. the; the          B. a; the         

C. the; a          D. a; a

22. Nowadays people have to pass various tests for professional ________ so that they can be    qualified for a well-paying job.

A. admission         B. permission      

C. certificates      D. perseverance