Dear Harry,

I am your friend, Li Hua. I feel so sorry about the case that I can't participate in your birthday party. And I want to give my congratulations to you. As I meet some frustration in my study, I decide not to go outside this days. And my parents are so busy with their work that they need me to help they to do the housework. It is a great pity for me that I can't attend your party. But I truly wish you to have a good time.