Definition
to encounter an unforeseen problem or get into unexpected trouble.
遇到（意外的）問題；陷入（意外的）麻煩
While sorting through old books, I ran across one that I thought I had lost.
在整理舊書時，我偶然發現一本我以為已經遺失的書。
He ran across an old friend on the street, which surprised him greatly.
他在街上偶然遇到一位老朋友，這讓他非常驚訝。
While browsing the internet, I ran across an interesting article that I couldn't resist clicking on.
在瀏覽互聯網時，我偶然發現一篇有趣的文章，忍不住點擊進去。