[問題]GWD 21-Q34

[lovingminami]

Scientists have dated sharp-edge flakes of stone found in the fine-grained sediments of a dry riverbed in the Afar region of Ethiopoa to between 2.52 and 2.6 million years ago, puching back by more than 150,000 years the earilest 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

答案是A 我選了C 請問一下C為何不對, 而A中的it 又代表什麼意思呢??
謝謝囉!!

[medi66]

Scientists have dated sharp-edge flakes of stone found in the fine-grained sediments of a dry riverbed in the Afar region of Ethiopoa to between 2.52 and 2.6 million years ago, puching back by more than 150,000 years the earilest 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

答案是A 我選了C 請問一下C為何不對, 而A中的it 又代表什麼意思呢??
謝謝囉!!

在CD 看到有人是這樣回覆的
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总算找到原文重现了;呵呵

This so-called Oldowan phase of toolmaking ... years ago, pushing back by more
than 150000 years the known date at which humans were making stone tools

可能是英文习惯用法:THE DATE AT WHICH

剩下B,C项.

B项与C项比,明显罗嗦.而且过去完成时说明发生在THE EARLIEST DATE之前就完成了,不合题意.SO......

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C 這個選項考推測動詞 感覺很像ETS愛考的考點
大家再繼續討論看看吧~

[crossover45]

我覺得答案是C耶
A的date後面又接when有語意重複的問題。C的humans are known to have made 用完成式很好啊，表示humans made的動作在are known之前就完成。另外which代替date作為are known的受詞，把at介詞提前符合ETS愛考的方式。

幾點意見供你參考

[clainotw]

我在 www.gmatclub.com看到別人討論這題目
幾乎全部的人都贊同答案是C
不過有個人說他在 powerprep上面碰過這個題目 他說官方給的答案是A

[dibert8]

覺得有可能是 (A) 也,因為 (C) 的時態似乎不合理,被動也不好.

(C) at which = at the date = 2.52 and 2.6 million years ago 過去時間用現在式?

(A) when {it is known that} humans made 把 'it is known' 看成插句(表示現在的看法),主要句意是 the earilest date when humans made stone tools.
when 引導名詞子句作 date 的同位語,補充說明 pushing... 之後的主要句意.

相關的討論請參見
天山7-41 http://www.formosamba.com/phpBB3/viewtopic.php?t=6183
GWD21-34 http://www.formosamba.com/phpBB3/viewtopic.php?t=9929