三令五申

sān lìng wǔ shēn

to order again and again

Character by character

三sān
three

令lìng
orders

五wǔ
five

申shēn
injunctions

学校三令五申，上课不许玩手机。

The school has repeatedly banned phones in class.

Tone: neutral.

From 《史记》: Sunzi explained his orders over and over before drilling the king’s palace women.

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