题目

完形填空As teenagers, you have many dreams. These dreams can be very big, such as winning the Nobel Prize,1they can be small. You may just want to become one of the top ten students in your class.Once you find a dream, what do you do with it?2 you ever try to make your dream come true?Follow Your Heart,3 Australian writer Andrew Matthews, tells us that 4 our dreams come true is life’s biggest challenge.You may think you’re not very good at some school subjects, or that it is impossible for you 5 a writer. These kinds of thoughts prevent you from reaching your dream, the book says.In fa2010年1月，湖南郴州市儿童医院被调查发现使用“工业氧”冒充“医用氧”，引发了全社会的关注．工业氧中存在一氧化碳、二氧化碳、乙炔等对人体极为有害的杂质，一旦病人吸入过量，会引发或加重呼吸系统的病症，甚至造成病人吸氧量不足而出现生命危险．（1）工业上通常利用分离液态空气的方法制取氧气，该方法是（填“物理”或“化学”）变化．（2）有一不纯的氮气，可能含有一氧化碳和二氧化碳，某化学兴趣小组为了探究其成分，设计实验如下图．请你参与探究．提出问题：该不纯氮气中是否含有一氧化碳和二氧化碳？设计实验：A中盛放的是澄清石灰水，B和E中盛放的均是足量氢氧化钠溶液，作用是；C中可盛放，用于除去气体中的水分．现象与结论：①若含有二氧化碳，你看到的现象是，反应的化学方程式是；②若含有一氧化碳，你看到的现象是．