HSK 7-9
刻苦
kèkǔ形
hardworking; assiduous
她学习刻苦，成绩稳步提高。
Tā xué xí kè kǔ, chéng jì wěn bù tí gāo.
She studies diligently, and her grades are steadily improving.
Say it
Hold the button, say it, then let go.
Other HSK words sharing a character
Also free:
Appears across levels (7-9) in the HSK 3.0 word list.