formpiston

例句：

1. 1. The engineis made up of several pistonsthat move in a cylinder.
   这台发动机由几个活塞组成，它们在一个气缸中移动。
2. 2. The piston rings are designed toprevent the engine from overheating.
   活塞环的设计是为了防止发动机过热。
3. 3. The pistonrod connects the piston to thecrankshaft, allowing it tomove up and down.
   活塞杆将活塞与曲轴连接起来，使其上下运动。