gravity flowing bed

例句：

1. 1. The gravityflowing bed is designed to filterout pollutants from the air.
   重力流动床设计用来过滤空气中的污染物。
2. 2.The gravity flowing bed has been proven tobe an effective way to treat wastewater.
   重力流动床已被证明是一种有效的废水处理方法。
3. 3.The gravity flowing bed is a popular choicefor industrial waste treatment.
   重力流动床是工业废物处理中的一种流行选择。