1、开头：Dear Mr/Ms XXX。2、正文：Today I'm writing to you to ask for a five-day leave.for I've got cold last night with carlessness.This morning my mother took me to see the doctor，who told me to stay in bed for some days.So I am very sorry to be absent from school.especially your interesting lessons.I'll be sure to make up for the missed lessons after I recover from the illness。3、落款：Yours ever，XXX。