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摘要

正acid rain: rainfall containing solutions of nitric and sulfuric acids 酸雨-Precisely how acid rain forms in the atmosphere is still a mystery to scientists … most experts believe that the current problem is traceable to electrical generating plants, industrial boilers and smelting plants that release sulfur dioxide （SO2） and nitrogen oxides （NO2） into the atmosphere, as well as acidic soots and traces of toxic metals such as