study diligently(assiduously) and train (/practise) hard ❍ 这些工人由于～，已成为高度熟练的技术人员了。As a result of their assiduous study,these workers have become highly skilled technicians.
勤学苦练
studying diligently and training hard
勤学苦练
study and practice diligently;study diligently and train hard; diligent study and painstaking training
勤学苦练qín xué kǔ liàn
形容勤奋学习，刻苦训练。study diligently and train hard, diligent study and strenuous training, study and practise hard