以下是引用许仙在2008-2-15 11:10:00的发言：楼上MM，我上面的回复写错了，是连加的会了，鸟飞的还是不会，等上考场看实际情况再说了。 同学们，来个语法： 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 大家觉得选什么?答案是C，date的前面可以加at吗？我做PREP语法的时候看到一个解释说不能直接说sb.is known to do...,要it is known that.....可是这题答案是C呀，？？？ 1. A最大的问题是歧义。when... 本应作定语，但也是个完美的状语从句，意思就变成：当知道人类造工具这件事情的时候，this finding pushes back....。同一个东西可能作两种成分，并导致两个不同的意思，这种表达方式在GMAT中是禁止的。B 就没这个问题，因为at which...只能作定语从句，不能作状语。 2. be known to have done sth的问题。我觉得，当be known 和 do sth的发生的时间一致时，用be known to do sth；而do sth发生在be known之前时，则要用be known to have done sth。这里的情形显然属于后者。 所以选C 附known to do sth的例句： 1. 大全748：...few people are known to have recovered from the disease once the clinical symptoms have appeared. 2. 大全849：...few people have been known to taste it for the first time without requesting more. 3. og49：......satellites now known to orbit the distant planet. 其实我也不太明白为什么，这是别人的解释，你参考一下吧 | 
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发表于 2008-2-15 12:19:00
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