假设你是李华，你在国际学校的朋友保罗邀请你下周日去他们学校参加文化交流活动，并发言介绍中国传统绘画，但是由于你的爷爷生病住院，你不得不谢绝他的邀请。请根据下面的要点用英语给保罗写一封回信。
要点：1. 谢绝保罗的邀请；
2. 说明你的理由；
3. 推荐你的同学安娜去演讲。
注意：1. 内容必须包括以上要点，可作适当发挥；
2. 文章条理清晰，意思连贯，语句通顺；
3. 词数不少于100，文章的开头和结尾已经给出，不计入总词数。
Dear Paul,
Thank you very much for your invitation.
______________________________
Yours,
Li Hua

One possible version:
Dear Paul,
Thank you very much for your invitation.
I'd love to accept it and take this chance to introduce traditional Chinese painting to foreign friends, but I'm sorry to tell you that I can't. My grandpa is seriously ill in hospital and I have to look after him. As for the introduction speech, I strongly recommend my classmate Anna who is the most suitable person to give the speech instead of me next Sunday. She began to learn painting at an early age and has a broad knowledge of traditional Chinese painting. She is very active and has perfect spoken English. I think she will help make your event a success.
Sorry again and all the best wishes to you.
Yours,
Li Hua