千钧一发

qiān jūn yī fà

hanging by a thread

Character by character

千qiān
thousand

钧jūn
weights

一yī
one

发fà
hair

在这千钧一发的时刻，司机踩住了刹车。

At that critical moment, the driver slammed on the brakes.

Tone: neutral.

From Han Yu's 一发引千钧, one hair holding 30,000 catties; 发 is fà, 'hair'.

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