Dear sir or madam:

　　the purpose of this letter is to recommend mr. x, a worthy candidate for admission to your graduate program.

　　mr. x have ever took my course "introduction to control". i was deeply impressed with him not only the good score "a" he got in the class but also thehighly active and devout attitude he learn control theory. sometimes, he came to my office to ask me some interesting questions about the control and system theories not mentioned in the autobiology of my class and to discuss the development and application of control theory in science and industry with me. he imagined this theory is truly an amazing subject. if people understand and use it very well, this world will get better. "well!" i thought, " this young man is really like control."

　　then he took part in my research "design of sinusoidal oscillators using the theory of variable structure systems" (published in the int. j. of electronics,1992,) to design the oscillator circuits. from simulating the circuits he designed with pspice to assembling the electronic elements. he shown me the enthusiam and hardily spirit in his  gettinga new idea or finding some questions,he always shared his opinion about how to overcome the error or improve the experiment results to  try-and-error and ameliorating the circuit many times, we finally got a refined but good-performance oscillator.

　　mr. x also got admirable grades in a couple of courses of control and systems, i truly believe he has strong learning capability and enthusism in this field. so i no doubt that he will become a good student in your esteemed department. should you need any further information about mr. x, please do nothesitate to contact me.

　　sincerely yours

　　xxx