Table: soo_locomotives
Columns: class
wheel_arrangement
fleet_number_s
manufacturer
year_made
quantity_made
quantity_preserved

Question: What manufacturer made 6 and preserved 1?
SQL: SELECT "manufacturer" FROM soo_locomotives WHERE "quantity_made" = '6' AND "quantity_preserved" = '1'

Question: How many did alco -schenectady preserve of class b-3?
SQL: SELECT "quantity_preserved" FROM soo_locomotives WHERE "manufacturer" = 'alco -schenectady' AND "class" = 'b-3'

Question: What manufacturer made class b-2?
SQL: SELECT "manufacturer" FROM soo_locomotives WHERE "class" = 'b-2'