litmus

石蕊化学

Litmus turns red in acid and blue in alkaline solutions.

石蕊在酸性溶液中变红，在碱性溶液中变蓝。

试金石、检验标准litmus test

The vote became a litmus test for the new leader's authority.

这次投票成了检验新领导人权威的试金石。

石蕊试纸litmus paper

She dipped a strip of litmus paper into the sample.

她把一条石蕊试纸浸入样本中。