proportioning pump

例句：

1. 1. The engineer designed a proportional pump to control the flow rate of the liquid.
   工程师设计了一个比例泵来控制液体的流速。
2. 2.The proportioning pump was used to mix different chemicals in the laboratory.
   比例泵被用来在实验室中混合不同的化学物质。
3. 3.The proportioning pump was essential for maintaining the balance of the chemical reaction.
   比例泵对于保持化学反应的平衡至关重要。