柯林斯词典litmus /ˈlɪtməs/ 1. N a soluble powder obtained from certain lichens. It turns red under acid conditions and blue under basic conditions and is used as an indicator 石蕊 返回 litmus剑桥词典a powder that is turned red by acid and blue by alkali 石蕊 litmus paper 石蕊試紙 a litmus test 石蕊測試 返回 litmus