This paper introduces a type of composed water-tube boiler that is fitted with a new type of cast iron air heater instead of the common cast iron economiser.是什么意思_This paper introduces a type of composed water-tube boiler that is fitted with a new type of cast iron air heater instead of the common cast iron economiser.在線(xiàn)翻譯_英語(yǔ)_讀音_用法_例句