用英语写请假条how to Ask for a leave in englsih

Dear Ms Ma,
I apologize that I cannot go to school today. Last night my mother had a high fever and coughed badly.
I think that she has got flu. She didn't have a good sleep and is very weak today, so I will go to Tiantan Hospital with my mother,
and then stay at home to attend her. Because of this I have to ask for leave. I will appreciate you very much if you can allow my leave.
Yours,
Li Li