◎ 题干
Earth is believed ______ by an object the size of Mars at some point in the distant past before its
surface cooled.
[     ]

A. to be hit
B. to have hit
C. to have been hit
D. to hit

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◎ 解析
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◎ 知识点
    根据魔方格专家分析,试题“Earth is believed ______ by an object the size of Mars at some point in the distant past before its surface cooled. [ ]A. to be hitB. to have hitC. to have b…”主要考查了你对  【不定式的完成式】  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。