affair 含义较广，侧重指已发生或必须去做的任何事情或事务。复数形式多指重大或较复杂的事务。
business 通常指较重要或较难而又必须承担的事情，也可指商事。
matter 普通用词，着重指一件考虑中的或需要处理的事。
concern 往往强调与个人或团体利害有直接或重大关系的事。
thing 用作“事情”解时，词义较笼统、含糊，多用于指不很具体的事。
参考例句
1. How do you possibly stay in business? 你们究竟是怎么在做生意的？
2. The core of our business is accounting. 我们业务的核心是会计工作。
3. Econometrics and business statistics involves the extraction of information from data. 计量经济学和商业统计涉及信息提取的数据。
英英解释
n.
1. a commercial or industrial enterprise and the people who constitute it
2. the activity of providing goods and services involving financial and commercial and industrial aspec
3. business concerns collectively
4. the volume of commercial activity
5. a rightful concern or responsibility
6. the principal activity in your life that you do to earn money
7. an immediate objective
8. incidental activity performed by an actor for dramatic effect
9. customers collectively
