[jiān kǔ zhuó jué]
（坚忍刻苦的精神超越寻常） staunch through trials and tribulations; endure hardship being prominent above all; endure hardship heroically; showing the utmost fortitude
an extremely hard and bitter struggle; a most arduous struggle
坚苦卓绝的斗争
a hard-fought battle
坚苦卓绝的战斗