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Scientists now believe that artificial-hip implants, previously thought to be safe, may actually increase the risk of cancer in recipients after about 45 years of use. Though these implants do improve the quality of recipient’s lives, the increased risk of cancer is an unacceptable price to pay for these improvements. , they should be banned.
Which of the following, if true, is the strongest counterargument to the argument above?
解释：此题中Therefore表明了因果关系。此题原因为：人造臀部虽然能够提高受体的生活质量，但是会在45年后增加引发癌症的机率。所以，这种技术应该被禁止。想削弱这个命题就是要为这个技术“辩护”。选一个为其辩护或者高唱赞歌的选项吧!
(A) Artificial-hip implant surgery can cause severe complications, such as infection, chronic fever, and bone degeneration, and these complications can themselves be crippling or even fatal.未唱赞歌。
(B) Almost all artificial-hip implant recipients receive their implants at an age when they are unlikely to live more than an
additional 30 years. 这样，受体在未到45年的时候就已经翘辫子了，因此此选项在为此种技术“辩护”
(C) Although artificial-hip implants increase the risk of cancer after about 45 year of use, a few of the cancers they induce are not fatal. 依然承认了得癌症的可能性，“辩护”力度不及B。
(D) Since artificial-hip implants are not very common, banning them would cause little hardship. 相对比较中性。
(E) Although the benefits of artificial-hip implant surgery have remained substantially the same over
the past decade, the price of the surgery has risen considerably. 此选项强调是此技术的缺点：价格太高此题的启示在于：从这四个错误的选项可以看出错误选项的类型：
1. 相反的选项，如削弱题中的支持类的选项。如此题中的A和E
2. 无关选项，如D
3. 与正确选项形成PK关系，但是相比之下没有正确选项符合要求。例子10：
Metropolis regulation limiting to four days the period during which milk can be sold to consumers after pasteurization is unreasonable. Under optimal conditions, pasteurized milk kept at 40 deGREes Fahrenheit remains unspoiled for at least 14 days. If Metropolis current limitation were changed to eight days, milk prices would drop, but product quality would be unaffected.
Which of the following, if true, would most seriously weaken the conclusion drawn above?
解释：此题中虽然没有具体的信号词表明其逻辑关系。但是可以看出：因为在最佳情况下，即在40华氏度保存牛奶，牛奶14天都不会变质。所以，作者认为可以如果把牛奶的保质期调整为8天，牛奶价格将会下降。想削弱此命题有以下几种思路： 1、否定前提：牛奶不可能在最佳条件下保存。
2、否定前提：即便在最佳条件下保存，牛奶8 (<14天)就变质了 3、否定结论：将牛奶保质期调整为8天，牛奶价格也不会下降以上任何一个思路都可以削弱该结论
(A) Most consumers keep milk no more than three days after purchase.
(B) A recent survey showed that 20 percent of Metropolis consumers favored extending the current limitation on the sale of milk to 8 days.
(C) Metropolis’ grocery-store owners would prefer small, frequent deliveries of milk to larger, infrequent deliveries.(D) Milk kept longer than 14 days after pasteurization generally presents no medical dangers if consumed. 支持了该结论 (E) In Metropolis, conditions for handling and storing milk after pasteurization are seldom close to optimum.
因此选择E，其它几个跟事先的思路不符例子