请高手列出it happen that的用法 以及例句``谢谢我问的是it happen that和to连什么用;;;

（与to连用）碰巧
I happened to be in the market yesterday when a fire started.
昨天发生火灾时，我正好在市场上
（与to连用）偶然发生；巧遇
I happened to be out when he called.
他来访时，恰巧我出去了。
用法实在找不到..
只找到这个,,,没办法拉...

It happened that I met my teacher on my way home
我在回家路上碰巧遇上我的老师.
It happened that she bumped into a tree.
她碰巧撞上了一棵树.