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.
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
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.
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。
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。