Dear Tom，
I am indeed very sorry that I can’t go to Beijing with you next week， which I have promised. I feel badly about it and want you to know what happened。
Just now， my cousin， Li Qiong， who left home to Australia for his further study last year，informed me that he will return this Saturday morning. And ask me to pick him up at the airport with his family. You know， we haven’t seen each other for nearly a year。
I sincerely hope you can accept my apologies and understand my situation. I would appreciate your allowing me to make another date to show you around Beijing. Once again， I’m sorry for any inconvenience caused。
Sincerely yours，
Li Hua