(事情)Word Power: thing

1. affair 事務: a situation being dealt with or considered (usu. pl. affairs)
e.g. Can you go to the office of student affairs for me?

2. accident 意外: something (bad) which happens unexpectedly
e.g. I found the secret by accident.

3. business 職責: the things you do
e.g. It's none of your business.

4. case 情形: a particular situation or example
e.g. There's no coffee left? In that case I'll have tea.

5. event 事件: something important or unusual happens
e.g. The World Games 2009 was the biggest event in Taiwan.

6. incident 事變: an event which is either unpleasant or unusual
e.g. The 228 Incident still has its influence in the politics.

7. issue 議題: a subject or problem people are talking about
e.g. Don't worry! It's just a side issue, not the main problem.

8. matter 事情: a situation being dealt with or being discussed
e.g. Her resignation is not going to help matters.

9. problem 問題: a situation that needs attention and needs to be handled
e.g. Do you know how to solve the problem?

10. thing 事物: used to refer to the general situation
e.g. Things have been going very well recently.

References:
1. 中國人大附中朱京力老師
2. http://dictionary.cambridge.org/