题目内容：
Perhaps the days will come ____ people will be able to breathe clean air in cities.A. as B. when C. while D. sine
参考答案：
选择题：Perhaps the days will come ____ people will be abl
- 题目分类：统招专升本-----英语
- 题目类型：选择题
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A. as B. when C. while D. sine