【答案解析】[范文]
Dear John,
   Congratulations upon having received your doctorate in electronic engineering from Tsinghua University. This is an achievement of your years of hard work and you can well be proud of it.
   As an old friend, I have witnessed your progress, and I would never forget the exams we had taken together and how much effort you had put. It's awesome that you can be accepted by and successfully graduate from such a first-rate university.
   The bright future, undoubtedly, is waiting for you. China needs a large number of professional personnel like you. Hope we can keep in touch regularly.