CREATE TABLE table_6703 ("Outcome" TEXT, "Date" TEXT, "Tournament" TEXT, "Surface" TEXT, "Partner" TEXT, "Opponent" TEXT, "Score" TEXT)

Which Opponent had a Surface of hard, and a Partner of maria elena camerin?
SELECT "Opponent" FROM table_6703 WHERE "Surface" = 'hard' AND "Partner" = 'maria elena camerin'
SELECT "Opponent" FROM "table_6703" WHERE "Partner" = 'maria elena camerin' AND "Surface" = 'hard'