dear mr/ms xxx;

　　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.

　　yours ever,

　　xxx.