How to complain if a teacher expels a student?

Um, the teacher wants to expel the student unless the student makes a big mistake or is frequently absent from class or truant. If you want to make a complaint, you can go to the local education bureau.

However, students are a vulnerable group compared to teachers. Don't bear the burden until the last moment. Be submissive, say good things, give something, and ask parents to help and beg for mercy.