1. Insufficient credits: In universities, there are certain credit requirements every semester. Students who don't have enough credits may fail. This is due to failure to pass the course, absence from the exam or failure to complete the required courses.

2. Too many failed subjects: University courses usually have certain credits and assessment requirements. Many students who fail in subjects will not meet the graduation requirements, thus being held back.

3. Repetition: Students who have been reread once, but still fail to meet the academic requirements in the next school year, will be reread.

4. Academic violation: Students who violate the school's academic integrity regulations, such as plagiarism and cheating, will face repetition punishment.