题目

During a winter storm in 1919, one dog managed to save the lives of the people on the ship Ethie. Today, people still tell the story of the dog.In December 1919, Ethie was travelling along the coast of northern Canada. Without warning, the ship ran into a bad storm. Because of high winds and heavy snow, the captain could not tell where he was going. Sailing too close to the shore (岸), the ship could not move because of some rocks. Ethie was in danger.The captain decided to save the people on his ship. He thought it was too dangerous to try to reach the shore by lifeboat, so he sent up flares5．我国自主研制的首颗“碳卫星”将于2016年8月发射，主要任务是监测各地区二氧化碳的排放，为节能减排等宏观决策提供依据，请回答下列问题：（1）大气中二氧化碳含量升高的一个主要原因是化石燃料的大规模开发使用． （2）固定和利用二氧化碳能有效减少空气中的温室气体．例如工业上利用CO2和NH3生产尿素的反应：CO2+2NH3$\frac{\underline{\;一定条件\;}}{\;}$CO（NH2）2+X，则X的化学式为H2O． （3）下列行为符合“低碳生活，保护环境”这一理念的是②（填序号） ①焚烧纸质垃圾   ②步行上学   ③用电动牙刷刷牙．