开始选c,但是仔细看完题目,定位在line 26-30,觉得应该选A
Finally,older production technologies often continue to generate toxic wastes that were not regulated when the technology was first adopted. New regulations have imposed extensive compliance costs on companies still using older industrial coal-fired burners that generate high sulfur dioxide and nitrogen oxide outputs, for example, whereas new facilities generally avoid processes that would create such waste products. C some plants still generate them是文章中没有提到的
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