gear-wheel Rockweel tester

例句：

1. 1.The car's engine is a complex gear-wheel system.
   汽车的引擎是一个复杂的齿轮系统。
2. 2. The mechanic replaced the worn gear-wheel with a new one.
   机械师用一个新的齿轮替换了磨损的齿轮。
3. 3. The engineer designed a new gear-wheel that would increase efficiency.
   工程师设计了一个新的齿轮，以提高效率。