假如你是李华，你请Smith外教本周六晚上一起吃饭，但是由于你的室友吴明在周五上午发生了车祸而受伤住院，需要你的照顾，你不能如期履约。请你给Smith先生写一封信并取消邀请，信中包括以下内容：
1．说明为什么道歉；
2．解释不能履约的原因；
3．取消邀请，另约吃饭时间；
4．100字左右。
Dear Mr. Smith，
It's kind of you to have accepted my invitation to dinner ____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________
Yours，
Li Hua
Dear_Mr._Smith，
It's_kind_of_you_to_have_accepted_my_invitation_to_dinner on this Saturday evening. But much to my regret, I may not be able to keep my promise because one of my close roommates was seriously injured in a car accident which happened on Friday morning and he is now in hospital. I must take care of him for several days. I am afraid I have to cancel my invitation. I do apologize to you for it and hope you can understand me. If you don't mind, I would like to invite you to dinner another day when Wu Ming feels better. Have a good weekend.
Yours，
Li_Hua