—Jim,have you finished reading Harry Potter and Half-Blood Prince?
—No.I my father on the farm all day yesterday.
A. would help
B. had helped
C. was helping
D. have been helping
网友回答
A. would help
B. had helped
(答案→)C. was helping
D. have been helping
解析：考查时态。过去进行时表示过去一直在进行的动作。