Question: Find the name of the ships that are steered by both a captain with Midshipman rank and a captain with Lieutenant rank.
SQL: SELECT t1.name FROM ship AS t1 JOIN captain AS t2 ON t1.ship_id  =  t2.ship_id WHERE t2.rank  =  'Midshipman' INTERSECT SELECT t1.name FROM ship AS t1 JOIN captain AS t2 ON t1.ship_id  =  t2.ship_id WHERE t2.rank  =  'Lieutenant'