问题补充:
Lisa, now stop for a short break. You should know that youall the morning.
A. are working
B. had been working
C. have been working
D. have worked
答案:
A. are working
B. had been working
(答案→)C. have been working
D. have worked
解析:考查动词时态。根据now stop for a short break,可知现在还在工作,再根据all the morning,可知整个早晨一直在工作,所以要用现在完成进行时态,表示从过去开始到现在一直在进行的动作。有可能还会进行下去。所以选C。