第一节 单项填空（共15小题；每小题1分,满分15分）
21. The vaccine (疫苗) is used to protect ______ whole population against H1N1 infection. And it
has proved to be ______ great success.
A. /; / B. the; a C. a; the D. the; /
22. --- Could you drive me to the supermarket at noon if ______.
--- Yes, certainly.
A. it is convenient of you B. it is convenient to you
C. you are convenient D. you are convenience
