CREATE TABLE ship (ship_id DECIMAL, name TEXT, type TEXT, built_year DECIMAL, class TEXT, flag TEXT)
CREATE TABLE captain (captain_id DECIMAL, name TEXT, ship_id DECIMAL, age TEXT, class TEXT, rank TEXT)

Find the captain rank that has no captain in Third-rate ship of the line class.
SELECT rank FROM captain EXCEPT SELECT rank FROM captain WHERE class = 'Third-rate ship of the line'
SELECT "rank" FROM "captain" EXCEPT SELECT "rank" FROM "captain" WHERE "class" = 'Third-rate ship of the line'