一成不变

一成不變
yīchéngbùbiàn
(idiom) immutable; impervious to change; set in stone

CEDICT

Entry Composition

1 一 yī
  1. one
  2. single
  3. a (article)
  4. as soon as
  5. entire; whole; all; throughout
  6. "one" radical in Chinese characters (Kangxi radical 1)
  7. also pr. yāo for greater clarity when spelling out numbers digit by digit
2 成 chéng
  1. to succeed
  2. to finish
  3. to complete
  4. to accomplish
  5. to become
  6. to turn into
  7. to be all right
  8. OK!
  9. one tenth
3 不变 bùbiàn
  1. constant
  2. unvarying
  3. (math.) invariant