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.