What was the 1989 result for the tournament with 1984 of a, 1985 of a, and 1990 of a?
CREATE TABLE "grand_prix_singles_tournament_timeline" (
  "tournament" text,
  "1983" text,
  "1984" text,
  "1985" text,
  "1986" text,
  "1987" text,
  "1988" text,
  "1989" text,
  "1990" text,
  "career_sr" text
);
SELECT "1989" FROM "grand_prix_singles_tournament_timeline" WHERE "1984"='a' AND "1985"='a' AND "1990"='a';