【答案解析】[范文] Dear sir， Please excuse my absence from class today because I got a bad cold yesterday evening and failed to fall asleep well in the night．I felt even worse this morning．There-fore，I had to go to the doctor to have myself thoroughly examined．Thus，I am writing to ask you for a day's sick leave and assure that I'll resume my study if I feel any better tomorrow． Sincerely, Xiao Ming