Who won the men's doubles before 1979 when carol silman prina ben shushan won the women's doubles?
CREATE TABLE "past_winners" (
  "year" real,
  "men_s_singles" text,
  "women_s_singles" text,
  "men_s_doubles" text,
  "women_s_doubles" text,
  "mixed_doubles" text
);
SELECT "men_s_doubles" FROM "past_winners" WHERE "year"<1979 AND "women_s_doubles"='carol silman prina ben shushan';