verb · to engage in physical exercise; to work out

他每天早上坚持锻炼身体。

verb · to develop one's skills, character, or willpower through experience or hardship

基层工作最能锻炼一个人的能力。

verb · to toughen or temper metal through heating and hammering

这种钢材需要经过反复锻炼才能成型。