下列净化水的常用方法中属于化学变化的是( )
--- Do you like watching TV? ---Yes, I. But only after I finish my homework.
Li Yan is my best friend. She comes a small village.
How is your father? Please say hello to ______ for me.
下列关于实验室制氧气并用排水法收集的实验操作先后顺序中不正确的是()
某无毒气体的密度约是空气密度的5/9,且极难溶于水,那么收集该气体的方法可采用 ①向上排空气法 ②向下排空气法 ③排水法()