The teacher invigilated in the 90 examination room of Quanjiao County, Anhui Province.

There are three invigilators in each examination room, and the main invigilator of each three groups will participate in the lottery 30 minutes before each exam. If the main invigilator draws 90 examination rooms, the exams will be invigilated by these three teachers, and lots will be drawn for each exam. You realize that the three teachers you met in the examination room this afternoon are only temporary, and you will draw lots again tomorrow. I wish you success in your exam!