The number of people diagnosed as having a certain intestinal disease has dropped significantly in a rural county this year , as compared to last year , health officials attribute this decrease entirely to improved sanitary conditions at watertreatment plants, which made for cleaner water this year and thus reduced the incidence of the disease. Which of the following, if true, would most seriously weaken the health officials' explanation for the lower incidence of the disease? 答案是C：Because of a new diagnostic technique , many people who until this year would have been diagnosed as having the intestinal disease are now correctly diagnosed as suffering from intestinal ulcers. 按照我的理解，现象是：许多被诊断为有某种肠道病的人大量减少，结论是：归因于水处理厂卫生条件的改善。 我认为weaken它的方法一共有两种：1.还有其他结论可以解释这个现象 2.这个现象是有偏差的。 答案是：以前被诊断为肠道病的人现在还是诊断出有肠道病。我怎么觉得对结论没什么影响啊？
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发表于 2009-5-2 01:19:00
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