bù biàn
constant
unvarying
(math.) invariant
yī chéng bù biàn
nothing much changes (idiom); always the same
stuck in a rut
bù biàn liàng
invariant quantity
invariant (math.)
bù biàn jià gé
fixed price
constant price
gèn gǔ bù biàn
unchanging since times immemorial (idiom)
unalterable
unvarying
monotonous