piston packing ring

例句：

1. 1. The piston packingring is essential for maintaining the engine's efficiency.
   活塞密封环对于保持发动机效率至关重要。
2. 2. The piston packing ring was designedto prevent oil from leaking into thecylinder.
   活塞密封环被设计用来防止油泄漏到气缸中。
3. 3. The piston packing ring was replacedafter a few months of usedue to wear and tear.
   由于磨损，这个活塞密封环在使用了几个月后被更换了。