—Was it there you were away to see your friend off?—I’m not sure . But when I got back i

问题补充：

—Was it there you were away to see your friend off?

—I’m not sure . But when I got back, it was gone.

A. that

B. which

C. where

D. while

答案：

A. that

B. which

C. where

(答案→)D. while

解析：句意：当你出去送别朋友的时候，它在那里吗？我不确定，但是，当我回来时，它就不见了。while 当…时候，引导时间状语从句，其余答案不符合题意，故选D