问题补充:
—Has Tom finished his task yet?
—I’m not sure. But he on it last week
A. was working
B. has been working
C. worked
D. had been working
答案:
(答案→)A. was working
B. has been working
C. worked
D. had been working
解析:考查时态。句意:——Tom完成了他的任务吗?——我不确定。但是他上周一直致力于这个任务。根据语境,说明与过去有关,且表示过去一段时间(last week)内一直在做某事,故使用过去进行时。