Can you tell me the titles of those courses?
SELECT T1.title FROM course AS T1 JOIN prereq AS T2 ON T1.course_id   =   T2.course_id GROUP BY T2.course_id HAVING count ( * )   >  1
titles of those courses that have more than one prerequisite refers to grouping by course_id in the prereq table and filtering for groups with a count greater than 1; course title refers to title in course table;