When I dropped in, Dr Smith , so we only had time for a few words.
A. just left
B. was just leaving
C. has just left
D. had just left
网友回答
A. just left
(答案→)B. was just leaving
C. has just left
D. had just left
解析：此题重点考查过去进行时的基本用法，表示过去某一时间正在进行的动作或存在的某种状态。