It is reported that in our country cities heavy air pollution that is 30 percent above the national standard or higher should try to meet standards by 2030.
A. suffering
B. suffer
C. suffered
D. are suffering
网友回答
(答案→)A. suffering
B. suffer
C. suffered
D. are suffering
解析：考查现在分词做定语：句意：据报道我们国家遭遇严重的空气污染在国家标准以上30%的城市到2030年要努力达到标准。这里是定语修饰cities，cities和suffer heavy air pollution是主动关系，用现在分词做定语，选A。