Question: What type of ship is a Kobben class vessel that has been in service longer than 2?
SQL: SELECT "Type" FROM "2-18952568-1" WHERE "In service" > 2.0 AND "Vessel" = 'Kobben class';

Question: What is the unit for a Submarine type ship from Norway?
SQL: SELECT "Unit" FROM "2-18952568-1" WHERE "Type" = 'Submarine' AND "Origin" = 'Norway';