◎ 题干
— Have the students finished decorating the hall for the celebration? 
— I've no idea. They ______ it yesterday afternoon.

 [     ]

A. did
B. have done
C. were doing
D. had done
◎ 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“— Have the students finished decorating the hall for the celebration?— I've no idea. They ______ it yesterday afternoon. [ ]A. did B. have done C. were 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。