We can have bluer sky if we create less polluted worldA. a；aB. a；theC. the；aD. the；the

We can have bluer sky if we create less polluted world．
A. a；a
B. a；the
C. the；a
D. the；the

(答案→)A. a；aB. a；theC. the；aD. the；the解析：在事物类别前通常用不定冠词a或an，辅音音素前用a，故本题选A。

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