很多时候第二种会简写为Ahlin, C. 很多期刊的reference都是这样简写的, 起码我所熟悉的APA是这样子。
    回到话题中，称呼教授一般有两种，Professor + First Name, 或者Dr. + Last Name, 一定要注意搭配，搞不好就会闹出笑话的。很多人有Middle Name，但只是不常用，经常只会出现initial.

    第一次写信，经常前面会加Dear表示尊敬，Dear Professor XX, 或者 Dear Dr. XX

    你弄懂了吗？

感谢宁婧同学的argument，我仿佛有些以偏概全，在网上搜了一下发现这个称呼真的是一件比较personal的事情，每个人都有自己的喜好。不过最保守的称呼方式，还是Dr.Last Name，这是被绝大多数人所认可的。

下面贴一些在网上找到的说明性文字，still open to discussion. 欢迎宁婧同学多多发言。下一期快出了...

What should students call their professors? When society used to be more formal, it was easy: professors were Dr. X or Professor Y. Today, some professors prefer to be called by their first names, and some do not. The professor-student relationship is a professional relationship, so you need to address your professor politely and with respect. Here are some guidelines:

1. As a rule of thumb, always address your professor formally, as Dr. X or Professor Y. If they invite you to address them by their first name, then use it. But it's polite to always assume the professor wants to be addressed formally, unless they tell you otherwise.
2. Consider the norms at your school. At some conservative schools, students never call professors by their first names. At some liberal arts colleges, it's the norm to address everyone informally. Ma'am and Sir might be appropriate as well, depending on where your school is, and manners never hurt..
3. Don't call professors Mr. or Mrs. This is a high school convention, not a college one. Your professor might feel disrespected if you refer to him or her by this less prestigious title. Also, many female college professors are liberal and do not like to be called Mrs.
4. What about TAs and instructors? Not everyone who teaches your classes are professors or PhDs, so this is confusing. Technically, a professor can refer to anyone who teaches college (as opposed to a Dr., who is someone with a PhD). It never hurts to call someone "professor." Many TAs will tell students what they prefer to be called, and if they don't, you might want to ask them politely.
5. Never assume it's okay to use a first name. Sometimes students assume it's okay to be informal if the professor is young, or female, or a minority, or nice, or whatever. This is not polite.
6. Call your professor something. Students sometimes feel so uncomfortable that they speak to their professors without using a name at all. This is pretty impersonal. Remember, if you're unsure, just use "professor."
7. This goes for emails too. Emails to a professor are a formal correspondence, and you should use good email etiquette and be as polite to your professor as you would be in the classroom. Unless your professor has invited you to use his or her first name, begin the email with, "Dear Professor X."
8. Don't judge professors harshly because they don't want you to use their first names. This doesn't mean your professor is arrogant. Many professors choose to use the title because it helps them maintain a formal tone in the classroom. This is the case with many female professors, especially young ones, who know they have to work a little bit harder than male professors to earn their students' respect.
9. If you're uncomfortable using the professor's first name, then don't. I invite my students to call me Naomi, but some students are more comfortable with formality. It's unlikely your professor will be put off if you use their formal title.
10. Don't be afraid to ask. You can always ask the professor how he or she would like to be addressed. Just ask politely.

http://www.suite101.com/content/what-should-i-call-my-professor--a9046

http://forum.wordreference.com/showthread.php?t=181545

http://www.formsofaddress.info/Professor.html