query: select avg(age) from student where stuid not in (select stuid from has_pet)
question: Are Finding that average ages of students do not have no pet.
query_toks: select avg ( age ) from student where stuid not in ( select stuid from has_pet )
query_toks_no_value: select avg ( age ) from student where stuid not in ( select stuid from has_pet )
question_toks: Are Finding that average ages of students do not have no pet.