题目

第二节：开放作文        请根据下面提示，写一篇短文。词数不少于50。        In your English class, your teacher shows you the following picture. You are asked to describe the picture and explain how you understand it.  答案：Possible versions:        In the picture we can see two men-a young man and an old man. The young man looks excited with the three big fish in his hand while the old man looks upset and angry carrying only a small fish with him. And the young man is running after the old man trying to explain something to him.        I think the picture conveys a message that everyone has his or her ad某无色气体中可能含有甲烷、一氧化碳、二氧化碳、氮气中的一种或几种，现将该气体依次通过下图所示装置，观察到：①A装置内未见有浑浊出现；②D装置内无水硫酸铜变蓝（无水硫酸铜遇水变蓝）；③最终收集到一定量干燥气体（假设每步反应都是完全的）．（已知浓硫酸可以干燥气体，氢氧化钠溶液可以吸收酸性气体）请回答下列问题：（1）由①可知原混合气体中肯定不含______；（2）由③可知原混合气体中一定含有______；（3）最终收集到的气体是______（不包括过量氧气）；（4）实验过程中记录的实验数据如下：D装置总质量E、F装置总质量反应前156.6g356.8g反应后158.4g361.2g则该气体的成分为：______．