external indicator

• 外指示剂

external indicator的用法和样例：

例句

1. Our goal is to obtain an indicator that can gauge concentrations.
   我们的目标是得到能够测量浓度的指示剂。
2. Upon the addition of a good starch indicator a blue solution results.
   加入好的淀粉溶液指示剂，这时溶液变成兰色。