Dear Mr.Zhang：

I’m Zhanglin。I came across an accident on my way home yesterday and fell off my bike。Fortunately，I was sent to the hospital immediately by kind-hearted people。After checking my body，the doctor told me that I was not hurt badly。However ，he adviced me to stay in bed for three days。So I write this later in order to ask for a sick leave 。I hope you can approve it！

yours Zhanglin

8th April