天山-7-41

aeoluseros

umm...有点眉目了，或许是因为有is和are的存在，所以at which/when只会修饰后者，否则的is和are应该换成was和were。所以是不会引起歧义修饰的。而A的错误应该仅在于1、when不如”“介词+which”“  2、be known to do在描述一件早已存在却现在才发现的事情时，才是更简洁地道的表达方法。

songlovegt

为什么通过is 和 are 就可以判断 at which/ when 是修饰的后者呢？版主再给讲讲

songlovegt

另问
状语从句到底可不可以修饰分词或者不定式？还是必须修饰完整的句子？

mastmyy

还是觉得the first date that对， 我记得最高级时用that.但没看到大牛们讨论这个问题。

songlovegt

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

又想到一点 when 修饰一段时间，at which 修饰一个时间点

260,000 - 252,000 = 8000 years

pushing back by more than 150,000
years

8000 years 相对于 150，000 years 只是一个零头，所以 the earliest date 的时间波动可以忽略，可以看成是一个时间点。at which 比 when 修饰准确。

另外状语从句不是必须修饰主句，应该也可以修饰分词，不定式
找到一个例子
GWD-29-Q10
The principal feature of the redesigned checks is a
series of printed instructions that the company hopes will help
merchants confirm a check’s authenticity, which includes reminders to watch the endorsement, compare signatures, and view the watermark while holding the check to the light.
A.        which includes reminders to watch the endorsement, compare signatures, and view
B.        which include reminders for watching the endorsement, to compare signatures and view
C.        by including reminders for watching the endorsement, comparing signatures, and viewing
D.        including reminders to watch the endorsement, comparing signatures and viewing
E.        including reminders to watch the endorsement, compare signatures, and view

while 引导的状语从句是和不定式to watch the watermark并列的

including reminders (to merchant) to watch the endorsement, compare
signatures, and view the watermark while holding the check to the light
这样的省略不常见，while不是必须和主句并列，而且逻辑上的主语可以都省

AlienX

LS的finding is interesting.
因為OG10#205E說although必須要有主句.
可是GWD-29-Q10的while沒有相對的主句...不清楚
- ETS是容許"當while表'同時'時, 可以不用主句"; OR
- ETS出GWD-29-Q10沒注意到, 因為這個while phrase是非underline portion; OR
- while phrase不是一個independent clause, 所以沒有這個限制

天蝎座1107

找到大部队了 待我好好研习

confetti0515

到底选哪个？GWD SC最累人的就是不知道答案是什么！！！

lupisces

PREP C

zuozuox

新prep1-256题,答案：C