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

Question: On what type of surface did they play on 13 February 1994?
SQL: SELECT "surface" FROM "singles_7" WHERE "date"='13 february 1994';

Question: In which tournament was Silke Meier the opponent in the final?
SQL: SELECT "tournament" FROM "singles_7" WHERE "opponent_in_the_final"='silke meier';