Dear Mr.Smith,
I am afraid that I cannot attend your birthday party tomorrow at 2 p.m.,because I have to take the college entrance test.However,I will send your birthday gift to you,and I hope you like it.
Happy Birthday,
(Your Name)
Dear Mr.Smith,
I am afraid that I cannot attend your birthday party tomorrow at 2 p.m.,because I have to take the college entrance test.However,I will send your birthday gift to you,and I hope you like it.
Happy Birthday,
(Your Name)