T-4-Q1 天山-7-41 again

shinycrystal

T-4-Q1
        天山-7-41

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.

1. when it is known that humans made

2. at which it is known that humans had made

3. at which humans are known to have made

4. that humans are known to be making

5. of humans who were known to make

why choose C?I'm puzzled...

Wait for your help,thanks!

xie999999999

 

[此贴子已经被作者于2007-4-20 21:06:00编辑过]

xie999999999

研究了半天，觉得so tricky：

原句date when it is known中when的修饰是有歧义的，可是是修饰date，也可以是修饰it is known；

the earlist date at which：如果date 是表示时期，用at肯定不对，因此the earlist date at which是表示最早的记录；

 关于时态，还是得建立在理解整句话的意思上，科学家确认尖石的年代是。。。，把人类最早使用石具的记录向前推了150000多年。（pushing back句是个小倒装，应为:pushing back the earlist date at which ...by more than 150000 years）

因此at which humans are known用现在时是对的，表示目前所有的记载，制造石器比are known要早，用现在完成时。

觉得这样的题也就作为练习吧，要真考的时候太难了。

shinycrystal

嗯，有道理！用现在完成时是关键！而且A when做定语从句还是状语从句不清楚。。。

要真考的时候碰到真是太难了！

sourirechen

还是觉得C不妥

1.date 可以用at which 修饰吗？这样修饰的话，date是什么意思呢？

2.至于时态，用过去时made也表示在known前发生的呵

不过A选项那个when确实也纠结，恳请NN再次解答。

北极虾仁

奇怪的答案