tom在1月20号举办生日宴会,他写信邀请李明参加,但李明不能参加这个生日宴会,

Dear Tom ,
　　First of all,thank you for inviting me to attend your birthday party to be held on Jan 20,2006.I would like to accept your warm invitation but I can not due to an earlier appointment.
　　Two weeks ago,I made an appointment with one of my high-school classmates.He will accompany his mother who suffers from cancer to Beijing to see a doctor.Since he is a stranger in Beijing,he asks me for help and I have consented.
　　Anyway I feel sorry for disappointing you.However please wait to receive my surprising gift for you by EMS on your birthday.Many Happiness returns of the day!
　　Sincerely yours,
　　Li Ming