|关注一亩三分地微博："Get the person's title correct. Some teachers at a university go by "Professor",some by "Dr.", and some by "Mr.", "Mrs." or "Ms." If you get it wrong, the person will assume that you don't know the difference between the titles, or that you don't care. He or she may even be offended. By the way, "doctor" is the Latin word for "teacher". It is a term of respect given to people who have completed a doctorate degree, and one of the few perks of spending 8+ years in college!"