— Have you known each other for long? — Not very long we started to work in the company.

问题补充：

— Have you known each other for long?

— Not very long, we started to work in the company.

A. after

B. before

C. when

D. since

答案：

A. after

B. before

C. when

(答案→)D. since

解析：since 是从属连词,引导时间状语从句,常与现在完成时连用。题中答语为省略句,补全为:We haven’t known each other very long. We have known each other since we started to work in the company.