CREATE TABLE table_36287 ("Outcome" TEXT, "Date" TEXT, "Tournament" TEXT, "Surface" TEXT, "Opponent" TEXT, "Score" TEXT)

Which Opponent has a Surface of hard on 28 august 1993?
SELECT "Opponent" FROM table_36287 WHERE "Surface" = 'hard' AND "Date" = '28 august 1993'
SELECT "Opponent" FROM "table_36287" WHERE "Date" = '28 august 1993' AND "Surface" = 'hard'