query: SELECT lname FROM student WHERE sex  =  'F' AND city_code  =  'BAL' UNION SELECT lname FROM student WHERE sex  =  'M' AND age  <  20
question: Find the last name student who either female (sex F) and living city code BAL or male (sex M) and in age below 20.
query_toks: SELECT lname FROM student WHERE sex = 'F ' AND city_code = 'BAL ' UNION SELECT lname FROM student WHERE sex = 'M ' AND age < 20
query_toks_no_value: select lname from student where sex = value and city_code = value union select lname from student where sex = value and age < value
question_toks: Find the last name student who either female (sex F) and living city code BAL or male (sex M) and in age below 20.