英语六级阅读模拟试题辅导练习 2017
   task 1
    Water problems in the future will become more intense and more
complex. Our increasing population will tremendously increase urban wastes,
primarily sewage. On the other hand, increasing demands for water will
decrease substantially the amount of water available for diluting wastes.
Rapidly expanding industries which involve more and more complex
chemical processes will produce large volumes of liquid wastes, and many of
these will contain chemicals which are po ...