无济于事

wú jì yú shì

of no use

Character by character

无wú
no

济jì
help

于yú
to

事shì
the matter

现在后悔也无济于事了。

There's no use regretting it now.

Tone: neutral.

Often 现在…也无济于事; 济 means 'help'.

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This idiom and thousands more are in Learn Chinese with Bao, with audio, pinyin and drills that make them stick.