Time Clash 时间冲突
This lets you know that you are trying to enroll into a course that occurs at the same time as a course your are already enrolled into and, therefore, you will need to select another class.
contravention 违反 违法行为
conflict 冲突（可以流血的）
contradiction 矛盾（逻辑上的）
inconsistency 不一致（前后不一,出尔反尔）
