prototype gear

例句：

1. 1. The engineer designed a prototype gear for the new car.
   工程师为新车设计了一个原型齿轮。
2. 2. The prototype gear was tested on the factory floor before being mass-produced.
   原型齿轮在工厂车间进行测试，然后才大规模生产。
3. 3. The prototype gear was a critical component in the development of the new machine.
   原型齿轮是新机器开发过程中的一个关键组件。