◎ 题干
Bob would have helped us yesterday, but he ________.
A.was busy B.is busy
C.had been busy D.will be busy
◎ 答案
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◎ 解析
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◎ 知识点
    根据魔方格专家分析,试题“Bob would have helped us yesterday, but he ________.A.was busyB.is busyC.had been busyD.will be busy…”主要考查了你对  【一般现在时】【将来进行时】【过去完成进行时】【过去将来时的被动语态】  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。