注意：此页面搜索的是所有试题
题目内容
（河南科技大学大学英语3(专升本)）
Perhaps the days will come ____ people will be able to breathe clean air in cities.
选项:
A:as
B:when
C:while
D:sine
选项:
A:as
B:when
C:while
D:sine
参考答案
