在军事术语上把核潜艇在海里的连续航行叫长行．为保证长时间潜行，在潜艇里要配备氧气的化学再生装置．制氧气方法有以下几种：①加热高锰酸钾；②电解水；③在常温使过氧气钠（Na202）与二氧化碳反应，生成碳酸钠和氧气；④加热氧化汞．其中最适宜在潜艇里制氧气的方法是哪一种？与其他几种方法比较，该方法有哪些优点？写出相关反应的化学方程式．
根据题意可知：③在常温下过氧气钠（Na202）与二氧化碳反应，生成碳酸钠和氧气，既不消耗能源又能消耗潜水艇中工作人员呼吸过程中产生的二氧化碳．因此是最适宜在潜艇里制氧气的方法，优点为：操作简便易行，不需消耗热能和电能，C02和O2组成内循环．
反应的化学方程式为：2Na202+2C02=2Na2C03+02．
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| The back door of the ambulance (救护车) was quickly closed and the driver ran to the front, 1 into his seat and started the engine (发动机). Inside were the 2 parents, Mr and Mrs Green, the mother holding their baby daughter Ally. The little girl had some food in her throat (喉咙) and could hardly breathe. The driver, Mr White, turned on his siren (报警器) and started speeding towards the nearest hospital, fighting against 3 . The cars ahead of him pulled out of the way as he 4 the ambulance through the busy traffic. From the back of the ambulance the parents were shouting at him to hurry, since Ally had almost stopped 5 . In front of him he saw some traffic lights with the red "STOP" lights shining. Mr White knew that he had no time to stop, so he drove straight past the traffic lights, looking to his left and right as he did so. Coming towards him from his right was a taxi. The taxi driver had the windows 6 , since the car was air-conditioned (开空调的), and he was playing his radio. He did not 7 the ambulance. The lights were green, so he drove straight on into the path of the ambulance. Mr White tried to stop his ambulance, but it was too late. It hit the taxi. Everybody was shaken but no one was hurt. Mr White turned to see 8 little Ally was. He was 9 to see relief (宽慰) instead of anger on the faces of the parents. "Look!" cried Mrs Green. "She is breathing again." "It must have been the crash," said her husband. "It took the food out of her throat." The baby's color was turning to normal, and she was crying in a loud but healthy 10 . They were all joyful, and quite forgot about the accident, the taxi, and the lines of people all around them. | ||||
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