CREATE TABLE "singles_15" (
  "edition" text,
  "round" text,
  "date" text,
  "against" text,
  "surface" text,
  "opponent" text,
  "result" text
);

Question: what is the surface when the opponent is selma babic?
SQL: SELECT "surface" FROM "singles_15" WHERE "opponent"='selma babic';

Question: what is the surface when the round is gii play-offs and the edition is 2009 fed cup europe/africa group ii?
SQL: SELECT "surface" FROM "singles_15" WHERE "round"='gii play-offs' AND "edition"='2009 fed cup europe/africa group ii';

Question: what is the date when the surface is clay and the result is 6–7 (4–7) , 1–6?
SQL: SELECT "date" FROM "singles_15" WHERE "surface"='clay' AND "result"='6–7 (4–7) , 1–6';

Question: who is the opponent when norway is against?
SQL: SELECT "opponent" FROM "singles_15" WHERE "against"='norway';