Unfortunately when I dropped in Dr. Green so we only had time for a few words.A. just

问题补充：

Unfortunately, when I dropped in, Dr. Green , so we only had time for a few words.

A. just left

B. has just left

C. had just left

D. was just leaving

答案：

A. just left

B. has just left

C. had just left

(答案→)D. was just leaving

解析：考查时态：句意：不幸的是，当我拜访的时候，格林先生刚要走，所以我们只有时间说几句话。所以在我去的时候，格林先生还没走，ABC都不对，而是将要走，用过去进行时，表示过去将来时，选D。