The ambulance was just arriving, for a worker, who the window on the second floor, fell off the window.
A. had been repairing
B. was repairing
C. has been repairing
D. would be repairing
网友回答
(答案→)A. had been repairing
B. was repairing
C. has been repairing
D. would be repairing
解析：考查时态。根据句意可知，工人修理窗户发生在掉落下来之前，即过去的过去，过去完成时