outside shell of firebox

例句：

1. 1. The engineer carefully removed the outside shell of the machine.
   工程师小心翼翼地拆除了机器的外壳。
2. 2. The scientist studied the structure of the outer shell of the planet.
   科学家研究了行星外层结构。
3. 3.The car's body is made of a strong metal, with an outer shell made of plastic.
   这辆车的主体是用一种坚固的金属制成的，外壳是由塑料制成的。