当机立断

dāng jī lì duàn

to decide on the spot

Character by character

当dāng
at

机jī
the moment

立lì
at once

断duàn
decide

他当机立断，马上送病人去医院。

He made a snap decision and rushed the patient to hospital.

Tone: positive (praise).

当 is dāng (at the moment); praises decisiveness in an emergency.

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