题目

现有的是①石油气②面粉粉尘③氮气④天然气⑤一氧化碳，当这些物质与空气混合，遇明火，有发生爆炸危险的是( )A. ①②③⑤ B. ②③④⑤C. ①③④⑤ D. ①②④⑤ 答案：【答案】D【解析】可燃性的气体及粉尘与空气或氧气混合后，遇明火或静电或电火花都可能发生爆炸。①石油气是可燃性的气体，正确；②面粉粉尘是可燃性的粉尘，正确；③氮气不是可燃性的气体，错误；④天然气是可燃性的气体，正确；⑤一氧化碳是可燃性的气体，所以正确。故选D。—It’s reported that doing eye exercises is no use for students. But I hear you have to do it every day.—You’re right. But it’s one of the _______ in my school.A. plans B. hobbies C. rules D. orders