懂中文 Dong Chinese

鐵杵成針

tiě​chǔ​chéng​zhēn

to study diligently

Definitions

铁杵成针 (鐵杵成針) 

tiě​chǔ​chéng​zhēn

see 磨杵成針|磨杵成针[mó​chǔ​chéng​zhēn]

Sources