问题补充：
If , please buy me a backpack while you are at the supermarket.
A. you are convenient
B. it is convenient to you
C. it is convenient with you
D. I am convenient to you
答案：
A. you are convenient
(答案→)B. it is convenient to you
C. it is convenient with you
D. I am convenient to you
解析：可联系答.案.网客服索取。
