prep08语法题--时态&修辞结构&代词

小目标750

Scientists have dated sharp-edged flakes of stone found in the fine-grained sediments of a dry riverbed in the Afar region of Ethiopia to between 2.52 and 2.60 million years ago, pushing back by more than 150,000 years the earliest date when it is known that humans made stone tools.

A. when it is known that humans made

B. at which it is known that humans had made

C. at which humans are known to have made

D. that humans are known to be making

E. of humans who were known to make

这道题我错选了A；  网上很多解释，但我觉得考场做题时想不到那么多。

想问下各位G友，以下思路是否可以：

划线部分修饰date ， 排除DE  that, of  不make sense

—》排除B  过去完成时不 make sense

—》  比较AC  选项A中“it”  没有指代对象    并且  it is known that humans made   没有  humans are known to  表达直接  ；  

选项C  更好地表达了一个时间顺序  “HUMANS ARE KNOWN TODAY THAT THEY MADE TOOLS IN PAST ”  现在知道了事实， 这个事实发生在过去   

—》 选C

也很想请教各位G友， 有什么更好的思路比较AC吗？   希望可以互相交流，谢谢！

Vita薇震天

发表于 2019-03-05 10:53:07
Scientists have dated sharp-edged flakes of stone ...

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