GWD第12套第1题提问——答案是什么？

Idontcare4u

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

根据我个人下载到的版本，此题的答案是C，但是我在别的地方看到有人讨论此题，说正确答案应该是A。
我自己i也偏向于选A。因为人们制造石器是发生过去的事情，应该用一般过去时，C的现在完成时用的太莫名奇妙了。
有没有人与我有相同的困惑？或者你知道正确答案究竟是A还是C的？
在此谢过大家！希望有好心人来帮忙看一眼！

上邪

it's in prep08, and the answer is C

the real problem with the construction in choice (a) is that the clause following "when" is "it is known".
in other words, that choice suggests that the fact is (was?) known at that date, an interpretation that clearly doesn't make sense in context.

Idontcare4u

可是按照你的说法，C选项难道不是这个意思吗？C选项不过就是把when换成了at which，把it is known that...的强调句换成了正常语序的句子，但是意思仍是，“在这一天，人们被知道做了石器工具”，所以这一天还是：被知道人们有这个能力的一天，而不是人们真正做石器的一天。
如果你说A是这样错的，那么C也是同样的错误啊。

秋晨小仔

同学，这里的it is known that怎么会是强调句呢。。。你确定？

我把prep笔记的讲解给你粘过来了，你看看吧~
A。关系代词用when和at which都是可以的；此选项表达的意思是A fact is known at the earliest date，逻辑含义错误。
B.at which it is known表达的意思是A fact is known at the earliest date，逻辑含义错误；主语从句的时态用过去完成时不够合理。
C.Correct；the earliest date at which humans are known to have made stone tools.=humans are known to have made stone tools at that date (the earliest date) – AlienX.
D.定语从句关系代词错误；are known to be doing sth.用法unidiomatic，要表示正在进行也只要are known to do即可。
E.date of + noun用法错误，其后面那个名词都是在某个时间出现的事件，如：date of birth、date of departure、date of marriage，而date of humans不是什么事件，所以不能说 date of；应该用are known to have made，因为known是发生在现在，make发生在known之前。

Idontcare4u

感谢楼上，这次看懂了！但是，那个逻辑错误说实话我还是觉得很难以理解。

windie

逻辑错误的意思是：fact被known不是在the earliest date.我的理解你可以借鉴一下

Idontcare4u

逻辑错误的意思是：fact被known不是在the earliest date.我的理解你可以借鉴一下

-- by 会员 windie (2012/5/12 15:42:27)

同学你的意思是不是：fact应该确切是发生在the earliest date，而不是be known在the earliest date?

kwok1123

我觉得LSS的意思应该是，the earliest date 是被现在的人所知道所推断，如果按照A的意思，在the earliest date人类就已经知道了他们的那个时代是制造石器最早的时代，所以逻辑错误。

jeffery2541

我想弱弱地说一句 划线部分应该是用来修饰date的吧 或者说是应该是一个修饰date的定语从句吧
A选项用了一个when引导的从句 我感觉这个when应该是引导时间状语从句的吧 不大能用来这样修饰date吧
C选项则用了which的非限定性定语从句来修饰这个date吧 至于那个完成时态 我是这样理解的 表达的是人类已经具备了制造stone tools这一能力 用完成时态不能算错吧 不能单凭这一点杀掉此选项
就这样吧~