范文一：
Dear Tom,
I’m very sorry that I can’t go on a trip to Beijing with you next weekend, which I have promised you. I’m writing to tell you the reason for it.(topic)
Just now, my cousin, Li Ming, who went abroad for further education last year, informed me that he would return the next Saturday morning. He asked me to pick him up at the airport with his parents. As you know, we haven’t seen each other for about a year, so I’ll have to help him in the first place.
I really hope that you can accept my apologies and understand me. I would appreciate it if you allow me to fix another time to show you around some places of interest in Beijing.
Wish you have a good time this weekend!
Yours,
范文二：
Dear ______,
①I am truly sorry that ______(道歉的原因).
②The reason is that ______(介紹原因). ③Once again, I am sorry for any inconvenience caused. ④Hope you can accept my appologies and understand my situation.
Yours sincerely,
Li Ming
范文三：
Dear Tom,
It’s a long time since we met last time and I miss you very much. hanks for your invitation. However, I regret to tell you that I can’t travel o America this winter holiday for some unavoidable reasons.
First of all, it’s the coming of the Spring Festival that makes me refer to stay at home rather than take a travel to America. As far as
we Chinese are concerned, the Spring Festival is a family time treasured
by us all. What’s more, the College Entrance Examination is coming. So
significant is it to me that I will attend some tutorial classes during this
winter holiday for some of my weak divisions. Taking all the above
factors into consideration, I have to say sorry again
Anyway, shall I make it after the Exam? I will appreciate it if you
can be my guide at the time. Yours
Li Hua