Directions: Your friend Xiao Feng invites you to attend his birthday party. But you are not able to attend it, Write a letter to him to
　　（1） express your regrets,
　　（2） state the reason,
　　（3） offer your congratulations.
　　You should write about 100 words. Do not sign your own name at the end of the letter. Use "Li Ming" instead. You do not need to write the address.