(2013·湖南，34)—I don't understand why you didn't go to the lecture yesterday afternoon.
—I'm so sorry.But I my homework.
A. had done
B. was doing
C. would do
D. am doing
网友回答
A. had done
(答案→)B. was doing
C. would do
D. am doing
解析：
考查动词时态。根据语境，对话中的第二个人昨天下午没去听课，而是在做作业，故使用过去进行时态，表示过去一段时间内在持续发生的动作，故选B。