At the time of the earthquake Jeff was still in his office. He to finish a project before

问题补充：

At the time of the earthquake Jeff was still in his office. He to finish a project before he left for the day.

A. has tried

B. had tried

C. has been trying

D. had been trying

答案：

A. has tried

B. had tried

C. has been trying

(答案→)D. had been trying

解析：指从发生地震之前的某一时候开始到发生地震时一直在努力完成一项计划，并且在发生地震时依然在办公室努力完成这一计划，所以要用过去完成进行时。