better quit while you are ahead

问题描述:

better quit while you are ahead
这里better 是什么词性?quit ahead不是副词吗?为什么ahead前面可以用you are呢?想了半天没有搞懂啊555

ahead adv. 领先地;占优势地, (可用于be后) be ahead 领先;占优势如:Australia were ahead throughout the game... 澳大利亚队在整场比赛都处于领先地位.Scotland were ahead in their European championship qualif...