Some Martian rock structures look strikingly like structures on Earth that are k

游客2024-09-13  9

问题 Some Martian rock structures look strikingly like structures on Earth that are known_____ by microbes.

选项 A、having been created
B、being created
C、to have been created
D、to be created

答案 C

解析 空格所在的定语从句为“sth. be known to do”结构,因此排除A、B项。其次,that指代地球上的岩石结构,与created之间存在被动关系,故要用被动式,C、D都符合。最后,当不定式动作发生在谓语动词的动作之前时,不定式需要用完成式,本题中,在人们已知前,岩石结构已经由微生物创造成,即created动作先于are known发生,所以选择C项to have been created。
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