happening, coming or done quickly and unexpectedly
"a sudden storm"
"a sudden decision"
"a sudden cure"
The sudden appearance made me start.
出自： J. Buchan
On a sudden impulse, he locked a master in a classroom.
出自： A. Thwaite
With a sudden switch of subject she enquired what had taken him to Perpignan.
出自： S. Hood
A fashionable London fop caught by the sudden downpour.
出自： R. Alter