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

游客2023-10-25 53

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。that指代structures on Earth，与created之间存在被动关系，故要用被动式，C、D都符合。地球的岩石结构早已由微生物创造出来，即created动作先于are known发生，故选C。

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