I’ve kept up a friendship with a girl whom I was at school twenty years ago. A. till B.

问题补充：

I’ve kept up a friendship with a girl whom I was at school twenty years ago.

A. till

B. with

C. about

D. since

答案：

A. till

(答案→)B. with

C. about

D. since

解析：因为表示“和某人在一起”用with sb.。