(1).take place 表示“发生、举行、举办”,一般指非偶然性事件的“发生”,即这种事件的发生一定有某种原因或事先的安排,例如：
Great changes have taken place in our hometown during the past ten years.
The Olympic Games of 2008 will take place in Beijing.
(2) .happen作“发生、碰巧”解,一般用于偶然或突发性事件,例如：
What happened to you?(一般不说：What did you happen?)
Maybe something unexpected happened.
I happened to see him on my way home.
= It happened that I saw him on my way home.
(3).occur作“发生、想到、突然想起”解,其意义相当于happen,例如：
What has occurred?(=What has happened?)
A big earthquake occurred (=happened) in the south of China last month.
It occurred to me that she didn’t know I had moved into the new house.
(4).come about表示“发生、产生”,多指事情已经发生了,但还不知道为什么,常用于疑问句和否定句,例如：
When Mother woke up,she didn’t know what had come about.
I’ll never understand how it came about that you were late three times a week.
Do you know how the air accident came about?
(5).break out意思为“发生、爆发”,常指战争、灾难、疾病或者争吵等事件的发生,也可以表示突然大声叫喊等,例如：
Two world wars broke out last century.
A fire broke out in the hospital in the mid-night.
After the flood,diseases broke out here and there.
She broke out,“That is too unfair!”