Four doors. According to the document "Interim Provisions on the Management of Student Status of Adult Higher Education in ludong university" issued by official website, ludong university (Lu Da Xiao Fa (2065438+07) No.60), in Article 16, students who have completed all the courses specified in the academic year teaching plan and passed the examination will be promoted. The number of courses that fail the make-up exam is less than 3 (including 3), and can also be upgraded. Those who still fail four or more courses in the make-up exam every academic year should repeat their studies, enroll in the same major in the next grade, and pay tuition according to the tuition standard of the year. If there is no follow-up major in the school, you can transfer to other similar majors in the school. Students must not repeat at school more than 2 times, otherwise they will be expelled. So ludong university will fail four courses.