以下是引用河西学校在2009-4-21 0:58:00的发言:256. (28362-!-item-!-188;#058&003003) (T-4-Q1 TS-7-41) 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 一般现在时与过去完成时混用,错。 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
是选C吧? 句子结构: Scientists have dated 。。。, pushing back 。。。 科学家确认了某东东的年代,让人类已知的制造石器的最早时间提前了XXX年。 pushing。。。是 分词伴随修饰,代表 逗号前面的这件事情 带来的具体结果是 逗号后的这句内容。
date后面需要定语从句补充说明,这是一个具体的时间点,一般用at which, 因此 只剩下B,C ; 但B:at which it is known that humans had made 时态错误了,用了had made , 这里没有出现“过去的过去”的时间比较,不需要过去完成时; 另外 it is known that 显得啰嗦。所以排除B。
C. at which humans are known to have made 时态正确,主句里用的是 Scientists have dated 是现在完成时, 后面陈诉一个事实,用现在时 are known.
个人看法,希望没误导。 如果我错了,赶紧提醒我啊,加油了!
确实选C AlienX斑斑的点评: AlienX斑斑: 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).这解释太经典了!!! |