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.(提出请假及时间) thanks. i will call you at 1:30 . or you can call me at any time.(等候答复)(many thanks. im looking forward to your kind answer.)(希望获准)
Dear Sir or Madam:
Dear Mr Li/Miss Li/Mrs Li,I beg to apply for two days’ leave/a week’s leave/7 days’ leave of absence（请假）from the 7th to 8th of this week. Because I was ill, I want to return/go home to see the doctor.
To support my application, I herewith/enclose the sick leave certificate.
I should be very much obliged if you will grant me my application. As regards the lesson to be missed during my absence, I will do my best to make them up as soon as I get back from leave.
March 6th, 20xx
Dear Mr Li,
I’m sorry to tell you that I have to ask for sick leave for the whole afternoon class. Because I have a heavy headache now and feel very sick. I think I have to ask for sick leave to go to hospital for medicine. I will attend the next day classes on time.