CREATE TABLE "singles" (
  "date" text,
  "tournament" text,
  "surface" text,
  "opponent_in_the_final" text,
  "score" text
);

Question: What type of surface was used for the carthage tournament on august 14, 1994?
SQL: SELECT "surface" FROM "singles" WHERE "tournament"='carthage' AND "date"='august 14, 1994';

Question: Which tournament has marielle bruens for the opponent in the final?
SQL: SELECT "tournament" FROM "singles" WHERE "opponent_in_the_final"='marielle bruens';

Question: What surface was used on may 13, 2007?
SQL: SELECT "surface" FROM "singles" WHERE "date"='may 13, 2007';