boiler barrel second course

例句：

1. 1.The boiler barrel is the main component ofthe steam engine.
   锅炉筒是蒸汽机的主要部件。
2. 2. The engineer inspected the boilerbarrel for any signs of wear.
   工程师检查了锅炉筒是否有磨损的迹象。
3. 3. The newdesign uses a more efficient boiler barrel tosave energy.
   新设计使用了更高效的锅炉筒来节省能源。