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Recently an unusually high number of dolphins have been found dead of infectious diseases, and most of these had abnormally high tissue concentrations of certain compounds that, even in low concentrations, reduce dolphins’ resistance to infection. The only source of these compounds in the dolphins’ environment is boat paint. Therefore, since dolphins rid their bodies of the compounds rapidly once exposure ceases, their mortality rate should decline rapidly if such boat paints are banned. Which of the following, if true, most strengthens
the argument?
A The levels of the compounds typically used in
boat paints today are lower than they were in
boat paints manufactured a decade ago. B In high concentrations, the compounds are
toxic to many types of marine animals. C The compounds break down into harmless
substances after a few months of exposure to
water or air. D High tissue levels of the compounds have
recently been found in some marine animals,
but there is no record of any of those animals
dying in unusually large numbers recently. E The compounds do not leach out of the boat
paint if the paint is applied exactly in
accordance with the manufacturer’s directions.
答案选C，不过我第一次做直接把C当作weaken the argument.原文最后一句不是说只有污染源cease，海豚的死亡率就下降。可是C的意思是污染源暴露在空气和水中有一段时间才能变为harmless,那意思就是在这一段时间内海豚的死亡率仍然是不变的，这不是和原文的结论相反么？
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发表于 2015-3-14 11:20:17
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