以下是引用Matrixrl在2006-11-7 20:35:00的发言：although fullerenes----spherical molecules made entirely of carbon---- were first found in the laboratory, they have since been found in nature, formed in fissures of the rare mineral shungite.Since laboratory synthesis of fullerenes requires distinctive conditions of temperature and pressure, this discovery should give geologists a test case for evaluating hypotheses about the state of the Earth's crust at the time these naturally occurring fullerenes were formed. which of the following, if true, most seriouly undermines the argument? a.cofirming that the shungit genuinely contained fullerenes took careful experimentation b.some fullerenes have also been found on the remains of a small meteorite that collided with a spacecraft. c.The mineral shungite itself contains large amount of carbon, from which the fullerenes apparently formed d.The natural occurring fullerenes are arranged in a previously unknown crystalline structure e.shungite itself is formed only under distinctive conditions. I would like to ask Matrixrl: In choice D, is it previously "unknown" crystalline structure or "known" in the original question? If it is previously unknown, it doesn't make sense, since previously unknown means it is now known. On the other hand, if it is previously known, then it can weaken the arguement by saying that there is no need to do any test any more b/c the structure has already been known. | 
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发表于 2006-11-8 21:01:00
