千锤百炼

1. thoroughly tempered (or steeled); finely honed

♦ 在艰苦环境中工作, 经过~, 他意志越来越坚强了。 Toughened by working under difficult conditions, his will-power became stronger.

2. (of literary works) be polished again and again; be revised and rewritten many times; be a finished product