一朝一夕

yī zhāo yī xī

overnight; in a short time

Character by character

一yī
one

朝zhāo
morning

一yī
one

夕xī
evening

学好一门外语不是一朝一夕的事。

You don’t master a foreign language overnight.

Tone: neutral.

Nearly always negative, 不是一朝一夕的事; 朝 is zhāo (morning), not cháo.

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