query: SELECT LName FROM Student WHERE age  =  (SELECT min(age) FROM Student)
question: What is the last name of the youngest student?
query_toks: SELECT LName FROM Student WHERE age = ( SELECT min ( age ) FROM Student )
query_toks_no_value: select lname from student where age = ( select min ( age ) from student )
question_toks: What is the last name of the youngest student?