CREATE TABLE table_68273 ("Unit" CLOB, "Type" CLOB, "Gross MW" CLOB, "Construction start" CLOB, "Operation start" CLOB)

Construction start of 1 december 1984 is what unit?
SELECT "Unit" FROM table_68273 WHERE "Construction start" = '1 december 1984'
SELECT "Unit" FROM "table_68273" WHERE "Construction start" = '1 december 1984'