query: SELECT DISTINCT stu_fname FROM student AS T1 JOIN enroll AS T2 ON T1.stu_num  =  T2.stu_num WHERE enroll_grade  =  'C'
question: What is the first name of students which got grade C in any class?
query_toks: SELECT DISTINCT stu_fname FROM student AS T1 JOIN enroll AS T2 ON T1.stu_num = T2.stu_num WHERE enroll_grade = 'C '
query_toks_no_value: select distinct stu_fname from student as t1 join enroll as t2 on t1 . stu_num = t2 . stu_num where enroll_grade = value
question_toks: What is the first name of students which got grade C in any class?