set off
phrasal verbPart ofset
set off — phrasal verb
1. to begin a journey, or to make something — like an alarm, a bomb, or laughter —
1.片語動詞
釋義
to begin a journey, or to make something — like an alarm, a bomb, or laughter — suddenly start.
例句
Roya set off for the train station before the sun had risen.
The smoke from the burnt toast set off every alarm in the house.