Question: What are the names of all students taking a course who received an A or C?
SQL: SELECT T1.stu_fname ,  T1.stu_lname FROM student AS T1 JOIN enroll AS T2 ON T1.stu_num  =  T2.stu_num WHERE T2.enroll_grade  =  'C' OR T2.enroll_grade  =  'A'