活瓣

例句：

1. 1. The doorhas a livening mechanism that allows itto open and close smoothly.
   这扇门有一个活门机制，可以平滑地打开和关闭。
2. 2. The valve is responsible for controllingthe flow of gases through the pipeline.
   阀门负责控制气体通过管道的流量。
3. 3. The hinge on the door is loose,causing it to stick slightly when opened.
   门上的铰链松动了，当打开时会稍微卡住。