1. Both students and teachers feel very sad when they lose. At this time, what they need is comfort, and then help students find out the problems and make up for them in future study.
2. Seriously hurt the self-esteem of students and parents, and failed the exam, which made students and parents feel very uncomfortable. The teacher's doing this is undoubtedly worse.
Parents and students easily do not match the teacher's education. Parents will not support teachers, but will resent them. Imagine which parent would like to see their child get hurt.
4. It is even more inappropriate to add words. Perhaps the teacher's original intention is good, but the effect is the opposite.
To sum up, teachers do not take off the above behavior.