By the time he got up, I for two hours in the factory.
A. have worked
B. worked
C. was working
D. had been working
网友回答
A. have worked
B. worked
C. was working
(答案→)D. had been working
解析：考查时态。本题的关键词是by，该词通常与完成时连用，句意：到他起床的时候，我已经在工厂里工作了两个小时了。他起床使用了过去时got up，我工作两个小时是在此之前，故使用了过去完成进行时的时态。故D正确。