◎ 题干
They _____ very busy last month. 
[     ]
A. are
B. were
C. be
D. have been
◎ 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“They _____ very busy last month. [ ]A. are B. were C. be D. have been …”主要考查了你对  【一般过去时】  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。