out和happen的區別？

break out，爆發;越獄;逃跑;擺脫

例句

The authorities have urged people to stock up on fuel in case hostilities break out.

當局已敦促人們儲存燃料，以防戰事爆發

happen，v.作為結果)發生;碰巧;恰好;

例句，

All these changes happened over a period of time.

所有這些變化都是在一段時間內發生的。