寻求happen to,happen about的区别

happen to 碰巧
基本句式为：
1.sb.+ happen+to do
2.it +happen+that+sb.+do
eg.I happened to meet him yesterday.
=It happened that I met him yesterday.
昨天我碰巧遇见了他.

happen about 应该可能不是一个短语吧...
about关于，相关...
也可能和happen to 一个意思吧