CREATE TABLE "singles_7" (
  "date" text,
  "tournament" text,
  "surface" text,
  "opponent" text,
  "score" text
);

Question: Who is the opponent for the game played on august 20, 2006?
SQL: SELECT "opponent" FROM "singles_7" WHERE "date"='august 20, 2006';

Question: On which Surface will Estrella Cabeza Candela play?
SQL: SELECT "surface" FROM "singles_7" WHERE "opponent"='estrella cabeza candela';