litmus test

柯林斯词典

1. N-COUNT If you say that something is a litmus test of something, you mean that it is an effective and definite way of proving it or measuring it. 立見分曉的檢騐辦法[usu sing, usu N 'of/for' n]
Ending the fighting must be the absolute priority, the litmus test of the agreement's validity. 停火絕對是第一要務，也是檢騐協約是否有傚的試金石。
The success of wind power represents a litmus test for renewable energy. 風能利用的成功是對可再生能源的一次立見分曉的檢騐。