Database: cs_semester
Question: Among the professors with more than average teaching ability, list the full name and email address of the professors who advise two or more students.
SQL: SELECT T2.first_name, T2.last_name, T2.email FROM RA AS T1 INNER JOIN prof AS T2 ON T1.prof_id = T2.prof_id WHERE T2.teachingability > ( SELECT AVG(teachingability) FROM prof ) GROUP BY T2.prof_id HAVING COUNT(T1.student_id) >= 2