工业上用的大量氧气，主要是用分离液态空气的方法制取的．这个方法利用了（　　）

A．分解反应

B．化合反应

C．液态氧和液态氮的密度不同

D．液态氧和液态氮的沸点不同

When I was a very young children,my father created a regular practice I remember well years late.Every time he arrived home at end of the day ,we’d greet het at the door.He would ask who we was and pretend not to knowing us,Then he and my mother would have had a drink while she prepared dinner and they would talk about his day and hers.While they chat,my father would lift my sister and me up to sit in the top of the fridge.It was both excited and frightening to be up there！

My sister and I thought he was so cool for putting us there.

9（）