Alice邀请你周日去参加她的生日会，但你因事而无法参加。请你表达歉意并说明原因。
Dear Alice，
Thank you very much for your invitation .I'd love to go to your party but I won't be available .My parents are very busy ，so I have to help to look after my little sister on Sunday . Also， my dog is ill and I must take it to see the doctor . I am really sorry that I can't go to your party . I will visit you another time and give you a gift . For now I will just say "Happy birthday!”
yours，
Jane
译文：
十分感谢你的邀请。我非常想去参加你的生日宴会，但是我没有时间。我的父母很忙，所以我必须在周日的时候照看我的妹妹，并且我的狗生病了，我需要带它去看医生。真的十分抱歉我不能去参加你的宴会，我会另外找个时间去拜访你，再给你生日礼物。但是现在我只能对你说声“生日快乐！”
