happen on

US /ˈhæp.ən ɑːn/
UK /ˈhæp.ən ɑːn/
"happen on" picture
1.

偶然发现, 碰巧遇到

to find or meet by chance

:
I just happened on this old book in the attic.
我只是在阁楼里偶然发现了这本旧书。
She happened on a beautiful antique shop during her walk.
她在散步时偶然发现了一家美丽的古董店。