扫描二维码，直接登录
题库 / Prep2008E1-SC-256
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.
when it is known that humans made
at which it is known that humans had made
at which humans are known to have made
that humans are known to be making
of humans who were known to make
题目分析：
本题相对来说比较难，有几个选项较难排除。
选项分析：
A选项：本选项是一个主语从句，句首的it是形式主语，还原为正常语序则有：
that humans made stone tools is known.
由于整个划线部分是一个定语从句，所以若将先行词补进来则有：
that humans made stone tools at the earliest date is known.
但实际上，本选项至少需要改为：
for humans to have made stone tools at the earliest date is known.
为什么一定要在主句部分用不定式短语呢？这点考查了不定式和从句的区别。用之于本题，本选项的意思是，人们知道的人类最早制造石器的时间（区别于be known for，那个是著名于…的意思，be known to do是被知道…的意思）。此时的know是看法类动词，被动语态下，看法类动词的约束力较强，宾语部分需用不定式的形式。（实际上，和我们高中学习的内容不同，在英语正规的文献中，很少有it is known that的形式，基本都是xxx is known to be，原因就是本选项所写的内容）
B选项：本选项错误同(A)。
C选项：Correct.本选项在语法和逻辑上均是正确的。
D选项：此处用了关系词that，最好改为at which或者是when，这是因为先行词 the earliest date应在定语从句中做状语；另外，to be making应改为to have make。不定式或分词短语中加have表示这件事是先发生于其主句的，即先时性，而加be表示是和主句同时发生的，即，同时性。显然地，在逻辑上，制造石器应该先发生于know这个事件。
E选项：of引导了一个所有格，也可以看作the earliest date的限定性定语。但是，此定语的核心词不正确。在之前的所有选项中，the earliest date定语部分的核心词均为动词know，本选项中核心词为humans（后面的是humans的定语从句）。在逻辑上，最早的时期应该是一件事的日期，而不是“人”的日期。
求你不要再提约束力这3个字了，我头要炸了。
for anybody who wants to know the answer, --- by Ron
probably the easiest way to go here is to remember this as an idiomatic usage of the construction "known to". if the action is in the present, then you use "known to VERB"; if the action is in the past, then you use "known to have VERBed". as far as i know, these are the only two possible forms.
谢谢你把Ron的答案写出来，约束力我也挺难接受的
登录 或 注册 后可以参加讨论
i think 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.
A选项的意思是 人类制造石质工具的这件事被知道的时间提前了 而不是人类制造石质工具的时间提前了
谢谢 懂了
登录 或 注册 后可以参加讨论
if the action is in the present, then you use "known to VERB"; if the action is in the past, then you use "known to have VERBed".
for anybody who wants to know the answer, --- by Ron
probably the easiest way to go here is to remember this as an idiomatic usage of the construction "known to". if the action is in the present, then you use "known to VERB"; if the action is in the past, then you use "known to have VERBed". as far as i know, these are the only two possible forms.
earliest date at which it is known的意思是“知道xxx”的最早日期（被提前）
earliest date at which xxx are known to的意思是已知的“xxx这件事发生“的最早日期（被提前）
A选项：when it is known that humans made意思是人类制造石质工具的【这件事被知道】的时间提前了 而不是人类制造石质工具的时间提前了，而文章实际要表达的是制造石器的时间
C选项：at which humans are known to have made 正确. 不定式或分词短语中加have表示这件事是先发生于其主句的，即【先时性】，而加be表示是和主句同时发生的，即，同时性。显然地，在逻辑上，制造石器应该先发生于know这个事件。
E选项：[of] humans who were known to make，of引导了一个所有格，也可以看作the earliest date的限定性定语。但是，此定语的核心词不正确。在之前的所有选项中，the earliest date定语部分的核心词均为动词know，本选项中【核心词】为humans（后面的是humans的定语从句）。在逻辑上，最早的时期应该是[一件事的日期，而不是“人”的日期]。
earliest date at which it is known的意思是“知道xxx”的最早日期（被提前）
earliest date at which xxx are known to的意思是已知的“xxx这件事发生“的最早日期（被提前）
错选A是因为其意思是人类制造石质工具的【这件事被知道】的时间提前了 而不是人类制造石质工具的时间提前了，而文章实际要表达的是制造石器的时间
earliest date at which it is known的意思是“知道xxx”的最早日期（被提前）
earliest date at which xxx are known to的意思是已知的“xxx这件事发生“的最早日期（被提前）
C和E：现在时known to do，过去式known to have done，后者对，因为发生在过去
朗文当代：be known to do something-Smoking is known to increase a person’s risk of developing lung cancer.
In more formal English, you say it is known that or it is known who/why/what etc:
It is known that the drug causes infertility. / It is not known how many people were killed.
ab选项还原：that humans made tools is known at the earliest date 意思是known这个事情发生的时间；原句表达的是做工具的时间即推前的是做工具的时间，而不是考古发现证据的时间humans are known to have made stone tools at the earliest date
for anybody who wants to know the answer, --- by Ron probably the easiest way to go here is to remember this as an idiomatic usage of the construction "known to". if the action is in the present, then you use "known to VERB"; if the action is in the past, then you use "known to have VERBed". as far as i know, these are the only two possible forms.
我的理解：A&B是It is xxxx that的强调句型，句意理解上为什么要强调known呢？
"A 错选 AB的意思是错的
AB的意思是知道的时间，而文章实际要表达的是制造石器的时间
修饰语必须离修饰对象很近，所以 date是修饰known的。
C 没选觉得应该用when，但实际上at which等价于when
D 前面是时间date，不可以用that，that只可以代替物
E 人类的日期 错误"
实际上，和我们高中学习的内容不同，在英语正规的文献中，很少有it is known that的形式，基本都是xxx is known to be，原因就是本选项所写的内容。
be known/thought/believed to do sth：
看法类动词的被动语态可以用不定式，如：James is believed to be a good guy.当我们说“詹姆斯被认为是一个好人时”，我们并没有预设“詹姆斯是一个好人”这件事是事实。换句话说，詹姆斯是好人这件事可能只是大家的看法，而并非实际的事实。因此，此时，看法类believe动词实际上就控制了“詹姆斯是好人”这件事的发生（如果大家不这么认为，那詹姆斯是好人这件事可能也就不存在了）。
when humans made stone, 而不是when a fact is known。修饰语应该尽可能靠近修饰对象，使逻辑清晰，如：
R：I read in today's newspaper that taxes are going to increase.
W：I read that taxes are going to increase in today's newspaper.
in today's newspaper应该靠近修饰对象read。
原句结构，可以调整为pushing back the earliest date by more than 150,000 years，即把the earliest date前移，这样就清晰了，划线部分是the earliest date的定语从句。
A：很少有it is known that的形式，基本都是xxx is known to be
时间状语，用when或in which
The earliest date when people used tools，when可以拆解成介词+which
The earliest date that people used tools，that只能替换人或物，这里缺的是时间状语，用when或in which
to have done something是不定式表达过去的唯一一种方式，所以这里的have done时态是正确的
A，when或者at which都可以。when可以指代整个时间状语，如on the day，which则只指代名词，需要补出时间状语里的介词。A补足就是：it is known that humans made stone tools at the earliest date，众所周知人类最早时候制造了石器。
B，had错误。全句只有一个另外的动词时has dated，是现在的动作，不能用had。
C，humans are known to have made stone tools at the earliest date。与A相比，二者被知道的对象不同，一个是某件事情被知道，一个是人类被知道做了某件事情。这里人类是知道的对象。
D，that只能指代名词，需要补足时间状语里的介词。humans are known to be making，making表示和are相同的时间框架，错误。
E，date of humans，人类的日期，错误。
pushing back by more than 150,000 years the earliest date at which humans are known to make stone tools.
by接数字，表示往回推了多少年，如：The population has been reduced by 1000.人口减少了1000.
这里将back前置了，正常语序是pushing the earliest date at which humans are known to make stone tools back by more than 150,000 years，将人类最早使用石器的日期往前推了15万年。at which做定语修饰the earliest date。
be known/thought/believed to do sth：
看法类动词的被动语态可以用不定式，如：James is believed to be a good guy.当我们说“詹姆斯被认为是一个好人时”，我们并没有预设“詹姆斯是一个好人”这件事是事实。换句话说，詹姆斯是好人这件事可能只是大家的看法，而并非实际的事实。因此，此时，看法类believe动词实际上就控制了“詹姆斯是好人”这件事的发生（如果大家不这么认为，那詹姆斯是好人这件事可能也就不存在了）。