书面表达 假如你是李华,你的英国朋友David邀请你今天参加她的生日聚会,但你因故不能赴约,100字左右,

dear david
i'm very happy to hear that today is your birday.may you happy birday.but i am very sorry that i can not go to your birthday party.you know that i have a examination about english tomorry morning.so i have to go over english.you know i am not good at english.beside i should have a good rest today evening.so i can't have fun with you.i hope you will have a nice party if you have free time i hope to have lunch with you.looking forward receiving your understand and reply.
yours
lihua
如有错误敬请原谅!