写一篇英语作文内容:你姑姑将从美国回来探亲，希望你去机场接她。但你从未见过这位阔别家乡二十年的姑姑。请写一封信欢迎她的归

Dear Mary
I have received your invitation. I'd love to take part in your birthday Party, but my Saturday has been occupied. I am sorry to say i will not come to your party. In the morning on Saturday I will attend the English competition. And in the afternoon on Saturday I have to go to the football club to play football. In the evening my grandpa will ask me to go to his house to have dinner with him.
Happy Birthday to you!
Yours friendly
Tom