What's the date that Morocco has an Against along with a surface of hard?
CREATE TABLE "singles_17" (
  "edition" text,
  "round" text,
  "date" text,
  "against" text,
  "surface" text,
  "opponent" text,
  "result" text
);
SELECT "date" FROM "singles_17" WHERE "against"='morocco' AND "surface"='hard';