题目

Some Martian rock structures look strikingly like structures on Earth that are known ______ by microbes.A. having been createdB. being createdC. to have been createdD. to be created

Some Martian rock structures look strikingly like structures on Earth that are known ______ by microbes.

A. having been created

B. being created

C. to have been created

D. to be created

题目解答

答案

C. to have been created

解析

本题考查动词不定式的被动完成形式在特定语境中的正确使用。关键点在于理解"be known"的用法以及动作的时间关系。

  • 核心思路：当主语是动作的承受者，且动作发生在"被知道"之前时，需用不定式的被动完成式（to have been done）。
  • 破题关键：明确"microbes"是动作的执行者，且结构的形成是已完成的动作，因此需体现被动和完成时态。

选项分析

  1. A. having been created

    • 错误原因：动名词完成式不能直接跟在系动词"be known"后，此处需用不定式。

  2. B. being created

    • 错误原因：动名词一般被动式表示动作正在发生，但题目强调"已知"的结果，需用完成时态。

  3. C. to have been created

    • 正确原因：不定式的被动完成式表示动作在"被知道"之前已完成，符合"微生物已创造结构"的语境。

  4. D. to be created

    • 错误原因：不定式的被动式表示动作尚未发生，与题意中"已知的结构"矛盾。