return-drain pump

例句：

1. 1. The return-drain pump is used to removewastewater from the system.
   回流泵用于从系统中去除废水。
2. 2. The return-drain pump is essential for maintaining proper waterflow in the system.
   回流泵对于保持系统内适当的水流至关重要。
3. 3. Thereturn-drain pumpwas designed to prevent backflowand ensure safe operation of the system.
   回流泵被设计成防止倒流，确保系统的安全可靠运行。