|
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.
请教为啥选C？先谢过！！
| 
京公网安备11010202008513号 京ICP证101109号 京ICP备12012021号
发表于 2013-5-17 15:01:26
收藏
收藏
楼主
