Name the opponents for may 18, 1997
CREATE TABLE "doubles_9_5_4" (
  "outcome" text,
  "date" text,
  "tournament" text,
  "surface" text,
  "partner" text,
  "opponents" text,
  "score" text
);
SELECT "opponents" FROM "doubles_9_5_4" WHERE "date"='may 18, 1997';