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题库 / OG2017V-CR-167
Colorless diamonds can command high prices as gemstones. A type of less valuable diamonds can be treated to remove all color. Only sophisticated tests can distinguish such treated diamonds from naturally colorless ones. However,only 2 percent of diamonds mined are of the colored type that can be successfully treated, and many of those are of insufficient quality to make the treatment worthwhile. Surely, therefore, the vast majority of colorless diamonds sold by jewelers are naturally colorless.
A serious flaw in the reasoning of the argument is that
comparisons between the price diamonds command as gemstones and their value for other uses are omitted
information about the rarity of treated diamonds is not combined with information about the rarity of naturally colorless, gemstone diamonds
the possibility that colored diamonds might be used as gemstones, even without having been treated, is ignored
the currently available method for making colorless diamonds from colored ones is treated as though it were the only possible method for doing so
the difficulty that a customer of a jeweler would have in distinguishing a naturally colorless diamond from a treated one is not taken into account
这道题讲的就是没有颜色的钻石可以加工来卖，有颜色的原石价值相对较低，但是可以通过加工把颜色去掉而且不容易被发现。但是，挖出来的原石里只有2%是带颜色且很多成色都不好，所以现在市面上的钻石都是本来就没有颜色的
要削弱，就需要考虑这个2%是不是有问题，只说了带颜色的只有2%，但是没说colorless且成色好的原石的比例是多少，如果后者的比例更低，那加工带颜色的原石的动机就很充分了。
本题是一个统计枚举类的题 要注意single不等于relative
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