1.(occur)发生
We cannot say for sure what will happen.我们说不准将会发生什么。
The accident happened at 10 o'clock.这起事故发生在10点钟。
We still don't know how the tragedy happened.我们仍然不知道悲剧是怎么发生的。
2.to happen to sb/sth
(befall)(好事或坏事偶然)发生在某人/某物身上, 降临在某人/某物身上
If we had been spotted at that point, I don't know what would have happened to us.如果我们当时被发现了, 我真不知道我们会出什么事。
3.(chance)碰巧；凑巧；恰好
I happened to bump into him in a shop.我在一家商店里和他偶遇。
If you happen to see Jane, ask her to phone me.如果你凑巧见到简, 叫她给我打个电话。
4.(be the case that)(尤指碰巧)正是如此
It happens that I know him.我正好认识他。