HSK V7-9
Correct

苦练

/ kǔliàn / 
Strokes

Definition

to train hard/to practice diligently/hard work/blood, sweat, and tears

Example

As a Verb
practise hard
1
Kǔliàn
苦练
jīběngōng
基本功

practise hard one's basic skills; train hard in basic skills