问题
Haze weather has become common in some major cities in China. We all wonder ________.
A:how is the air polluted
B:what can we do with the bad weather
C:why the air is polluted seriously
D:what are the real reasons;
B:what can we do with the bad weather
C:why the air is polluted seriously
D:what are the real reasons;
正确答案是：
