Dear Mr. Peter,
I would like to know if I could ask for a casual leave of absence for one day on April 4th,this Wednesday.
This morning I received a telephone call from my dentist, urging me to come to his practice for immediate treatment of my teeth. I have been experiencing a stinging pain, depriving me of my sleep during the past fortnight. Concerning my workload: As Wednesday is not as busy as the other weekdays, I think a one-day leave this Wednesday may be the best solution.(简述请假事由)I apologize for the inconvenience my absence from work may cause.(致歉)
Thanks. I will call you at 1:30 p.m. or you can call me at any time.(等候答复)(Many thanks. I'm looking forward to your kind answer.)(希望获准)
Earnestly yours，
Li Hua