一成不变 (yī chéng bù biàn)

(idiom) immutable; impervious to change; set in stone

Character breakdown

一 (yī) · 1 strokes

A single horizontal stroke, representing the number one.
成 (Chéng) · 6 strokes

Depicts defending city walls (丁) with an axe (戌). 丁 also represents the sound. Based on the original meaning "city", now written as 城. The current meaning is a phonetic loan.
不 (bù) · 4 strokes

Pictograph of sepals of a flower. The modern meaning "no" is a phonetic loan.
变 (biàn) · 8 strokes

Simplified form of 變. Phonosemantic compound. 夂 represents the meaning and 䜌 represents the sound.

世界是一成不变的吗？当然不是。
(idiom) immutable; impervious to change; set in stone
shì jiè shì yī chéng bù biàn de ma ？ dāng rán bú shì 。