苦練

苦练
kǔliàn
  1. to train hard
  2. to practice diligently
  3. hard work
  4. blood, sweat, and tears

CEDICT

Entry Composition

1 苦 kǔ
  1. bitter
  2. hardship
  3. pain
  4. to suffer
  5. to bring suffering to
  6. painstakingly
2 練 liàn
  1. to practice
  2. to train
  3. to drill
  4. to perfect (one's skill)
  5. exercise
  6. (literary) white silk
  7. to boil and scour raw silk