Leave the premise
Don't say that you have a cold, fever, headache and brain fever, but say it seriously and convince the teacher.
preparatory work/be about to work
Before you are going to ask for leave from the teacher, don't tell the teacher in a hurry. You should write a leave note to the monitor and say that you are not feeling well.
Reasons for leave
Now it's the content of the note. It says, don't say common diseases. If you want to ask for leave, say that you have conjunctival stones in your eyes and go to the hospital immediately.
Aftercare service
I stayed up late that night and went to school with red eyes the next day to ensure that the teacher would not doubt.