sac tube

例句：

1. 1. The squeaky sound of the sac tube is a sign that something is wrong with the machine.
   这个吱吱作响的气囊管声是机器出了问题的标志。
2. 2. The sac tube was used to transport food and supplies during the war.
   在战争中，气囊管被用来运输食物和物资。
3. 3. The sac tube was removed from the engine to replace the worn-out piston rings.
   从发动机中取出了气囊管，以替换磨损的活塞环。