Dear Mike,

I am terribly sorry to tell you that I am unable to attend your birthday party next Thursday evening. That is owing to the fact that my mother suddenly fell ill and was taken to the hospital this morning. I have to go there immediately and take care of her. According to the doctor in charge, it will take a few days for her to recover and I can’t leave her alone in hospital.

I really regret that I cannot go to celebrate your birthday personally. I have chosen a small gift for you and will send it to you tomorrow to show my best wishes. May you have a happy birthday. Besides, please give my regards to our friends when you meet them at the party.

题目分析：这是一篇提纲类作文。假如你的朋友Mike邀请你参加他的生日Party，你因故不能参加。请你写封信向他道歉并说明情况。内容提示：母亲生病住院需要照顾。买了件礼物寄去以示祝贺。需要写的内容已经粗略给出，需要我们翻译成完整通顺的句子，适当添加些内容，使文章更充实。写作时注意准确运用时态，上下文意思连贯，符合逻辑关系，不能出现文章脱节问题。尽量使用自己熟悉的单词句式，同时也要注意使用高级词汇和高级句型为文章润色。注意要求的词数100词左右，不要太多也不要太少。

【亮点说明】I really regret that I cannot go to celebrate your birthday personally.这里含有一个宾语从句。Besides, please give my regards to our friends when you meet them at the party.这里含有一个时间状语从句。