Excessive investment in education.

The state has invested a lot of manpower, material resources and financial resources in nine-year compulsory education. If students are allowed to repeat a grade again, it will be clear at a glance that the classroom must be rebuilt, and then there are hardware and software facilities such as tables and chairs, office supplies and computers. Will buy, will recruit teachers, will expand the scale of education. Obviously, this requires huge investment!

Keep education fair.

Learning the same knowledge for the second time is bound to be more solid and detailed than learning it only once. Therefore, if some students fail to repeat the grade and some students don't, it can be imagined that this is extremely unfair to students who only study once. Therefore, in order to maintain the fairness of education, nine-year compulsory education stage is not allowed to repeat grades, except in special circumstances.