．The highest award was given to Anna who so hard on the project for years and at last h

问题补充：

．The highest award was given to Anna, who so hard on the project for years, and at last her efforts paid off.

A. has worked

B. worked

C. was working

D. had been working

答案：

A. has worked

B. worked

C. was working

(答案→)D. had been working

解析：考查时态，句意;最高奖项被授予安娜，她从事这个项目多年，至少努力没白费，关键的句子：her efforts paid off.用过去时，而一直努力是发生在pay off，之前，用过去完成进行时。选D。