書到用時方恨少 (syu1 dou3 jung6 si4 fong1 han6 siu2) — When you need to apply some knowledge and you regret not acquiring enough of it in Cantonese
syuˉ¹書dou˗₃到jungˍ₆用siˎ₄時fongˉ¹方hanˍ₆恨siuˊ²少简 书到用时方恨少
Mandarin Pinyin: shu1 dao4 yong4 shi2 fang1 hen4 shao3
Meaning of 書到用時方恨少
nounWhen you need to apply some knowledge and you regret not acquiring enough of it
nounto regret not having studied harder in the past and only realising now that you need to use that knowledge