题目内容
If you live in Changchun, you may notice that the air in winter is not as _______as it is during the summer.
A.clean B.cleaner C.cleanest D.cleaning
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题目内容
If you live in Changchun, you may notice that the air in winter is not as _______as it is during the summer.
A.clean B.cleaner C.cleanest D.cleaning