Everyone in this country should work hard and do what they can against national smog.
A. fight
B. fought
C. fighting
D. to fight
网友回答
A. fight
B. fought
C. fighting
(答案→)D. to fight
解析：句意：这个国家的每个人都应该努力工作尽最大的能力来对抗全国范围的大雾。这里do后面是宾语从句what they can，惨后面省略了do，后面是不定式做目的状语，所以选D。