问题
单项选择题
干背式锅炉和湿背式锅炉的区别在于（）。
A．干背式锅炉的烟气是干的，而湿背式锅炉的烟气是湿的
B．干背式锅炉的烟室布置在烟气的第一、二回程之间，而湿背式锅炉的烟室布置在第二、三回程之间
C．炉胆后部的折烟室是否布置于锅水中
D．烟气温度低时用干背式锅炉，烟气温度高时用湿背式锅炉
答案
参考答案：C
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干背式锅炉和湿背式锅炉的区别在于（）。
A．干背式锅炉的烟气是干的，而湿背式锅炉的烟气是湿的
B．干背式锅炉的烟室布置在烟气的第一、二回程之间，而湿背式锅炉的烟室布置在第二、三回程之间
C．炉胆后部的折烟室是否布置于锅水中
D．烟气温度低时用干背式锅炉，烟气温度高时用湿背式锅炉
参考答案：C
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| Life today has brought new problems. One of 1 problems is pollution. Water pollution 2 our rivers and lakes dirty. It kills our fish and polluted our 3 water. Noise pollution makes us 4 louder and become angry more easily. Air pollution is the most serious kind of pollution. It's bad for all 5 things in the world. Cars, planes and factories all pollute our air every day. Sometimes the polluted air is 6 it is like a quilt over a city. This kind of quilt is 7 smog (烟雾). Many countries are making rules to fight pollution. Factories must now clean their water before it is thrown away, and they mustn't blow dirty smoke into the air. We need to do many other things. We can put waste things in the dustbin and not throw it on the ground. We can go to work by bike or with our friends in the same car. If there are 8 people driving, there will be less pollution. Rules are not 9 . Every 10 must help fight pollution. | ||||
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