◎ 题干
The discovery was made_______, which we hadn’t expected .
A.on purposeB.at presentC.in advanceD.by accident
◎ 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“The discovery was made_______, which we hadn’t expected .A.on purposeB.at presentC.in advanceD.by accident…”主要考查了你对  【介词和介词短语】  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。