試比較happen、 occur、 take place這三個詞語.

TAKE PLACE is more formal than HAPPEN.
Use TAKE PLACE about events that have been planned,
eg. The poicare tying to prevent the demonstration taking place.

and use HAPPEN especially about things that have not been planned or that people do not expect.
eg. The accident happened at 2 pm yesterday.
What' happened?

OCCUR is more formal than HAPPEN.
use OCCUR especially about changes, chemical reactions, and other things that happen naturally.
eg. Major earthquakes like this occur very rarely.