train of gears

例句：

1. 1. The car's engine is a complex train of gears that powers the wheels.
   这辆车的引擎是一个复杂的齿轮组，驱动车轮。
2. 2.The train of gears in the transmission system is responsible for converting the engine's power to the wheels.
   传动系统中的齿轮组负责将发动机的动力转换为车轮。
3. 3.The train of gears was designed to make the shifting process smoother and more efficient.
   齿轮组的设计是为了使换挡过程更平滑、更高效。