Dear professor,
I am the chairman of the Students’ Union of Foreign language school in Peking University. We are to hold an English speech contest next week. I am writing to ask whether you can honor us to be a judge for the competition.
The contest will be held next Sunday, Dec, 20. 2012 in the Room 200, Teaching Building No. 3 . It will begin at 6:30 and last for 3 hours. Participants will be from different majors in our university. Judges to be invited include another three professors who are very familiar to you.
We would be greatly honored if you can show your presence and provide us with your valuable comments. Please contact us at 1234567 if you can come.

 Yours sincerely,
　  Li Ming