◎ 题干
I’m sorry I delayed_________ your letter because I have been quite busy these days.
A.to answerB.to have answered
C.answeringD.answered
◎ 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’m sorry I delayed_________ your letter because I have been quite busy these days.A.to answerB.to have answeredC.answeringD.answered…”主要考查了你对  【动词短语】【动词】  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。