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.
语法 Sentence Correction-1761
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正确的用户笔记
ocean09960802 2016-05-31 16:00:23
用形式主语+is known+主语从句累赘 这句的意思变为是在那个时间知道（人类制造石头工具）这件事的
瑞雪兆丰年 2016-07-15 20:29:46
The difference between A and C is that A. When it is known THAT humans made... THAT is used here to modify whatever comes before the word. Therefore the emphasize is the timing,not the actual subject of human making tools. C. is correct because it put the emphasize right back to the subject matter--- HUMAN MAKING TOOLS!
goahead 2014-07-24 19:29:32
A fact is known at the earliest date
queenkat 2016-10-24 20:34:15
用形式主语+is known+主语从句累赘 这句的意思变为是在那个时间知道（人类制造石头工具）这件事的
糯米团子QUQ 2016-10-04 22:29:50
AB是意思是这个date是“人类造石器开始于什么时候”的这件事情 被 众所周知的时间，而不是指古人类开始造石器的时间。
阿卜灵 2016-09-04 19:01:08
earliest date when it is known that 变成了 sth. is now at the date.... 但是c里主语是humans，更清晰
shisu0610041 2016-08-30 18:50:15
it is known that ...，表明是得知消息的最早时间，逻辑错误
梅干菜要和gmat分手 2016-07-29 11:05:21
*：事实上在看这两个结构时，可以把be known to这个类似助动词的成分去掉；由于跟在be known to后面的动词要用原型，所以去掉be known to以后就可以单纯地比较have done和do，have done所表示的发生时间比do所表示的发生时间要早，如果事件发生在过去就用have done，发生在现在就用do。同时如果be known to do/have done sth后面接状语那么修饰的是do/have done，而不是known.
Goooaway 2016-06-11 14:03:59
http://www.manhattangmat.com/forums/scientists-have-dated-sharp-edged-flakes-of-stone-found-in-t9546.html
Sparrow_7 2016-05-25 22:39:23
此选项表达的意思是A fact is known at the earliest date，逻辑含义错误？？？
LancyXu 2016-05-18 15:43:14
这句的意思变为是在那个时间知道（人类制造石头工具）这件事的
