天山-七-41

[starterk]

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

雖然可以理解C正確
但請問一下
A錯在哪裡

[frozenrain]

when 不能做 date 的關係代名詞

[林小馬]

請接續前人討論喔
謝謝啦
http://www.formosamba.com/phpBB3/viewtopic.php?t=6183