Dear XXX Name:

I would like to request a day leave of absence for sickness.

I am XXXX and I am writing this letter to inform you that my daughter(son), XXX, studying in your class was diagnosed with flu,cold（感冒） and advised to take bed rest till he/she gets cured completely. I am fearing to send him/her to school as flu is a communicable disease.

（接下来一段是如果很严重）

I kindly request you to grant him/her leave till he gets completely cured and also to stay under continuous medical supervision to get quicker recovery. Thanks for considering my request. Thanking You,

Sincerely,

Your Signature