◎ 题干
I _______ my homework at nine o'clock last Sunday morning.
[     ]
A. am doing
B. was doing
C. do
◎ 答案
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◎ 解析
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◎ 知识点
    根据n多题专家分析,试题“I _______ my homework at nine o'clock last Sunday morning. [ ]A. am doing B. was doing C. do …”主要考查了你对  【过去进行时】  等知识点的理解和应用能力。关于这些知识点的“档案”,你可以点击相应的链接进行查看和学习。