单项选择题In the text of iExplore 2, the author mainly discusses ______. A、the causes and severity of light pollution B、the causes and effects of light pollution C、the causes, severity and impacts of light pollution
多项选择题在探索中国社会主义建设道路过程中，毛泽东提出，社会主义又可分为（）两个阶段。
