国外教授给出的推荐信建议

The One-Minute Rule
When I'm on the committee, I try to read every application; when I chair it, I make sure I do, some multiple times. That's many hundreds of applications in under a month. Factor in lots and lots of late letters, classes, etc., and it's clear I have to work pretty fast.
For the first pass—deciding whether the application deserves more time or not—I can afford to spend no more than about 6-7 minutes per application. (Keep in mind I've read maybe a few thousand applications, so I've had practice.) If I decide the application is promising, I may spend over half an hour (in some cases, days!) on it. But in those first 6-7 minutes, I have to:
• eyeball the student's research record
• form a summary of the transcript
• glance at the standardized test scores
• determine whether the statement is promising
• get the gist of 2-3 letters of recommendation
In practice, that means I have about one minute to devote to the first reading of your letter. Now think about whether your letter works in this context. (For instance, some letter writers put a big, prominent paragraph of boilerplate legalese at the beginning of their letter, which I have to read before I realize it's irrelevant. Could you have buried that in a postscript? Was that the best use of my minute?)

关于任课老师的写作：
Naturally, your most significant contact with the student is likely to be in courses. Yet what could be a rich source of description is often the poorest: Mor Harchol-Balter reports that at CMU, they call a certain class of these “DWIC” letters (“did well in class”), which are effectively useless.
Give us context. What textbook did you use? How much of it did you cover? Did the student take it earlier than usual?
Don't just report the grade; put it in perspective. How many students got that grade or better? If your transcript isn't nuanced (e.g., at Brown we give only letter grades with no +/- decorations), fill it in. Did they do an exceptional job at something? (Tell us what they did!) Were they biased towards some aspect of your class? (For instance, in my programming languages course, some take much better to the theoretical aspects, while others prefer the systems work. The transcript won't reveal this, but it's extremely valuable information for a professor trying to decide whether or not to recruit a student.)

关于研究经历的写作：
At a highly-competitive university like Brown, we want to know the student's research potential. The best assessment of this is what they have already done. If you are their research advisor, you have a special obligation to them (and to us) in your letter:

• describe their work in your own words
• tell us what the student's contribution was
• tell us whether it succeeded or failed
• if it's ongoing, tell us why you think it will succeed
We rarely expect the ideas to have originated from the student, but we would like to see signs that they took ownership of the project, improved it in some way, refined the idea, and so on. Finally:
• put any publications in context
Students don't always know how to do this. If you published a paper on the work, tell us about the quality of the venue. In particular, students are poor at telling different kinds of publications apart (tech report from conference poster from research paper) and may even try to hide the distinction (I've seen this happen). Help us understand what they really accomplished.
If you run a summer research center, you may get bombarded with letter requests from each of your students. I have seen such people write perfunctory one-paragraph letters. These hurt students, and are ultimately unethical. Someone gave you money to run that center; when you asked for it, you took on an obligation. Fulfill it, or else get out of the way. There are plenty of others who will gladly put that money to better use.

还有关于工作经历的推荐信的写作要点：
An important special case is the corporate letter: when you, the letter-writer, work in industry and have no academic affiliation. Many corporate letters (like many academic letters, but more so) tend to be vapid, clearly written in a different culture and for a different audience. Unless they actually did academic research with you, here are some suggestions for improving them.
A common mistake is to focus on teamwork. This is important even in academia, but often this is the primary focus of the letter, which makes it less valuable. Of course we care about it, but it's secondary to their technical skills.

• Tell us if they learned something particularly quickly, mastered a complex technology, or solved a problem others were stuck on. Give us a paragraph of details.
• If you have a concrete reason to evaluate research potential, do so concretely. Otherwise, don't bother. -baidu 1point3acres
• Give us a brief bio-sketch, including educational qualifications.
• Put the applicant in context, and tell us the context. It's fine to relate it to your own student days, or to your experience hiring students. E.g.:
Compared to the students I studied with at Cucumber and Melon University, and the ones I now recruit from there, I would put him in the top 10%.