◎ 题干
— I dropped in at your house at about ten last night, but you weren't in. 
— I ______ regular exercises at the club.
[     ]
A. did                        
B. was doing
C. had done                  
D. have been doing
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◎ 解析
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◎ 知识点
    根据魔方格专家分析,试题“— I dropped in at your house at about ten last night, but you weren't in.— I ______ regular exercises at the club. [ ]A. didB. was doing C. had done D. ha…”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。