刻苦钻研 kè kǔ zuān yán

DEFINITIONS

  1. to study diligently

CHARACTERS

刻 kè
HSK 3
carve, engrave; quarter hour
苦 kǔ
HSK 4
bitter; hardship, suffering
钻 zuān
HSK 6
drill, bore; pierce; diamond
研 yán
HSK 4
grind, rub; study, research