discharge indicator

例句：

1. 1.The engineer used a discharge indicator to monitor the level of pollutants in the air.
   工程师使用排放指示器来监测空气中污染物的水平。
2. 2.The company has installed a new discharge indicator system to improve environmental compliance.
   该公司已经安装了一个新的排放指示系统，以提高环境合规性。
3. 3.The research team discovered that the discharge indicator was not functioning properly, which led to further investigation.
   研究团队发现排放指示器无法正常工作，这导致了进一步的调查。