问题补充：
Could you drive me to the supermarket after supper if ?
A. it is convenient of you
B. you are convenient
C. it is convenient to you
D. you will be convenient
答案：
A. it is convenient of you
B. you are convenient
(答案→)C. it is convenient to you
D. you will be convenient
解析：句意：如果方便的话，晚饭后你能开车带我去超市吗？这里是if引导的条件状语从句，it在从句中是形式主语，指如果这件事对于你方便。用故选B。
