down tube

例句：

1. 1. The engineer carefully inspected the downtube for any signs of damage.
   工程师仔细检查了管道，以寻找任何损坏的迹象。
2. 2. The down tube was used to transportwater from the well to the house.
   管道被用来将水从井输送到房子。
3. 3. Down tubes are often used inplumbing systems to prevent leaks.
   在水管系统中，常使用管道来防止泄漏。