1.表示“某地(某時)發生了什么事”,常用“sth.+ happen +地點/時間”這一結構來表達,此時主語應是事情.例如：

　　The story happened in 1998

　　.這個故事發生在1998年。

　　An accident happened in that street.

　　那條街上發生了一起事故。

　　2.表示“某人出了某事(常指不好的事)”,要用“sth.+ happen+to sb.”這一結構來表達.例如：

　　A car accident happened to her this morning.

　　今天上午她發生了交通事故。

　　What happened to you?你怎么啦?

　　3.表示“某人碰巧做某事”,要用“sb.+ happen+ to do sth.”這一結構來表達.例如：

　　I happened to meet a friend of mine in the street yesterday.

　　昨天我碰巧在街上遇到了我的一個朋友。

　　4.happen表示“碰巧或恰巧發生某事”時,還可用“It happens / happened that...”這一結構來表達。例如：

　　It happened that Brian and Peter were at home that day.

　　碰巧那天布萊恩和彼得在家了。

　　It happened that he had to take part in a meeting that afternoon.

　　碰巧那天下午他不得不參加一個會議。

　　注：that從句中的主語是人時,此種結構可以與“sb.+ happen + to do sth.”結構互換。例如：

　　It happened that Brian and Peter were at home that day.

　　= Brian and Peter happened to be athome that day.

　　5.happen為短暫性動詞，不能與表示一段時間的狀語連用。