GWD21-34

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GWD 21-34

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  (C)

E. of humans who were known to make

i TOTALLY HAVE NO IDEA ABOUT THIS PROBLEM.HELP

tomasy

我选了A

carlito

晕！！牛牛赶紧解释一下！！

jinni

C

这里还有一个主要问题：A/B都没有指明when/at which是修饰从句中的it is known（知道“人类用石器”的时间）还是humans (had) made（人类用石器的时间）. 属修饰歧义错误。

winniebear0202

我看到的答案是A阿。

hwhhs

.

hwhhs

.