砥砺琢磨

Explanation: Sato: carving and polishing jade. Analogy to hone their character, continue to make progress in their studies. 　　Source: Cai Dong Pan, "the Republic of Kingdoms" one hundred and eightieth back to the government and all the weight of expectations of students, where repeated application is hereby decree, the solid phase has been warning, reluctantly become useful, its temper Sato, earnestly warned not negative meaning. " 　　Examples: Government and all the weight of expectations of students, where repeated application is hereby decree, the solid phase has been warning, reluctantly become useful, its ~, earnestly warned not negative meaning. (T. T. Pan, "the Republic of Kingdoms" one hundred and eightieth back)