tandem pumps

例句：

1. 1. The tandem pumps are designed to work together in a pair.
   双人泵设计成可以一起工作。
2. 2.They installed the tandem pumps at the hospital.
   他们在医院安装了双人泵。
3. 3. The tandem pumps were used to pump water from the well.
   双人泵被用来从井里抽水。