1).take place 表示“發(fā)生、舉行、舉辦”,一般指非偶然性事件的“發(fā)生”,即這種事件的發(fā)生一定有某種原因或事先的安排,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“發(fā)生、碰巧”解,一般用于偶然或突發(fā)性事件,例如：
What happened to you?(一般不說：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.