只 要 功 夫 深 鐵 杵 磨 成 針

只要功夫深，鐵杵磨成針

只要功夫深，铁杵磨成针

zhi3 yao4 gong1 fu5 shen1 , tie3 chu3 mo2 cheng2 zhen1

If you work at it hard enough, you can grind an iron bar into a needle. cf idiom 磨杵成針|磨杵成针, to grind an iron bar down to a fine needle (idiom); fig. to persevere in a difficult task to study diligently