-----Tom. You look very bored and tired.
-----Yes, I ______ my father on the farm until seven o’clock this morning.
A. have been helping B. had helped C.was helping D. am helping
-----Tom. You look very bored and tired.
-----Yes, I ______ my father on the farm until seven o’clock this morning.
A. have been helping B. had helped C.was helping D. am helping
C
由表示过去的时间状语until seven o’clock this morning可知, 前面用过去进行时。本题注意不要受思维定势的影响而用现在完成进行时，要深入体会动作的时间性。