一試便知龍與鳯 [－试－－龙与－]

Jyutping jat1 si3 bin6 zi1 lung4 jyu5 fung6
Pinyin yī shì biàn zhī lóng yǔ fèng

Definitions (CC-CANTO)
  1. one can tell the wheat from the chaff with just one trial [written and colloquial]