Hi,Mr.wang ,i am Mary ,i had a bad cold today, i am not feel well,my mother said i must stay in bed,maybe today and tomorrow i can't go to school,when i feel better ,i will go to school at once.
Dear Mr .Wang,
I'm not feeling well this morning and it turned out that I caught a bad cold.The doctor said I had to stay in bed and have a good rest for two days.As a result,I'm sorry I can't go to school today. So I ask for leave for two days.
Mary