What's Round has a Surface of hard and Opponent of Jelena Simic?
CREATE TABLE "singles_17" (
  "edition" text,
  "round" text,
  "date" text,
  "against" text,
  "surface" text,
  "opponent" text,
  "result" text
);
SELECT "round" FROM "singles_17" WHERE "surface"='hard' AND "opponent"='jelena simic';