coincidence

It was a pure coincidence that both brothers bought the same car on the same day.

(Chinese) 两兄弟在同一天买了同样的车纯属巧合。

Meeting my old teacher in a foreign city was a strange coincidence that I didn't expect.

(Chinese) 在异国他乡遇见我以前的老师是一个我没想到的奇妙巧合。