Who won the men's double when Chou Tien-Chen won the men's single?
CREATE TABLE "previous_winners" (
  "year" real,
  "mens_singles" text,
  "womens_singles" text,
  "mens_doubles" text,
  "womens_doubles" text,
  "mixed_doubles" text
);
SELECT "mens_doubles" FROM "previous_winners" WHERE "mens_singles"='Chou Tien-chen';