ㄏㄣˋhènㄊㄧㄝˇtiěㄅㄨˋㄔㄥˊchéngㄍㄤgāng

恨铁不成钢
  1. 無法比喻努力不滿惋惜迫切希望所長 年輕崇尚享樂人生態度老一輩有種恨鐵不成鋼感慨」。

lit. to hate iron for not becoming steel, to feel resentful towards sb for failing to meet expectations and impatient to see improvement (idiom)​