indicator electrode

例句：

1. 1. The indicator electrode is usedto measure the concentration of pollutantsin water.
   指示电极用于测量水中污染物的浓度。
2. 2. The indicator electrode was used todetect the presence of bacteria in the sample.
   指示电极被用来检测样本中细菌的存在。
3. 3. The indicator electrode was used to indicatethe direction of the current flow.
   指示电极被用来指示电流流动的方向。