cog-wheel casing

例句：

1. 1. The engineer was working on the new car's gearbox casing.
   工程师正在修理新车的齿轮箱壳体。
2. 2.The old car had a worn out gearbox casing that needed to be replaced.
   旧车有一个磨损的齿轮箱壳体，需要更换。
3. 3.The mechanic inspected the gearbox casing for any signs of wear or damage.
   机械师检查了齿轮箱壳体是否有磨损或损坏的迹象。