Dear XX:
How are you doing?
I am xx in your xxx class(在您的xx课里面，这个通常需要说明一下吧。). I want to apologize for the exam from last week. I missed the exam cause i was sick. i waited ouside of our classroom from 4:00 to 4:30 pm but no one was there， so i left.
And also i went home because it was dragon boat festival it is a very important festival for chinese. I was not in school this morning so i missed the class.
I am really sorry about that.
Regards
