千錘百鍊

- （多次鬥爭和考驗） thoroughly tempered; well-seasoned; much-steeled; go through fire and water; be repeatedly [thoroughly] tempered; by persistentknocking into shape; be steeled over and over again; severe training and hammering

- （多次精細修改） be polished again and again; be revised and rewritten many times; be highly finished