CREATE TABLE table_name_90 (tonnage VARCHAR2, built VARCHAR2, ship VARCHAR2)

The ship SSBergensfjord built before 1973 has what tonnage?
SELECT tonnage FROM table_name_90 WHERE built < 1973 AND ship = "ssbergensfjord"
SELECT "tonnage" FROM "table_name_90" WHERE "built" < 1973 AND "ship" = "ssbergensfjord"