Definition
to unexpectedly encounter someone familiar
無意間碰見（某人）；不期而遇（某人）
I ran across an old friend at the store.
我在商店裡無意間碰到了一位老朋友。
She ran across her classmate on the street.
她在街上無意間碰到了她的同學。
I ran across a former colleague at the library yesterday.
我昨天在圖書館裡無意間碰到了一位前同事。