题目

 “BANG!” the door caused a reverberation. “Never set foot in this house again!” shouted Father. With tears welling（涌出） up in my eyes, I rushed out of the house and ran along the street. A young father who held a child in his arms walked past me．I felt as if I saw my childhood from another space：happy and harmonious.        But now I don’t know whether it is because I have grown up or because Dad is getting old．We are just like two people coming from two different worlds．It feels like there is an iron door between us that can never be opened．     I wandered金属镁条在空气中燃烧后生成的固体产物有：MgO、Mg3N2、C，该实验不能说明空气中含有的气体是（　　）A．O2B．CO2C．N2D．He