(of a situation or an event) to have existence or come into existence

No one knows exactly what happened but several people have been hurt. 没人确切了解发生了什么事，只知道有数人受伤。

Anything could happen in the next half hour. 接下来的半小时内什么事都可能会发生。

A funny thing happened in the office today. 今天，办公室里发生了一件有趣的事。

I don't want to think about what might have happened if he'd been driving any faster. 我不愿意去想假如他再开快些会怎么样。

to do or be by chance

[ + to infinitive ] They happened to look (= looked by chance) in the right place almost immediately. 他们碰巧几乎一下就找对了地方。

[ + (that) ] Fortunately it happened (that) there was no one in the house at the time of the explosion. 幸运的是，爆炸发生时，屋子里没有人。

[ + that ] It just so happens that I have her phone number right here. 非常凑巧，我正好有她的电话号码。

She happens to like cleaning (= she likes cleaning, although that is surprising). 她恰恰就喜欢打扫卫生。

I happen to think he's right (= I do think so, although you do not). 我真的认为他是对的。

As it happened (= although it was not planned), I had a few minutes to spare. 我碰巧有几分钟空闲。

happen along/by (somewhere) 碰巧来到

happen on/upon something/someone 偶然发现，偶然遇到

perhaps

Happen it'll rain later on. 过一会儿可能会下雨。