Who is listed under mens singles when womens has wang nan zhang yining?
CREATE TABLE "table1_28138035_27" (
  "year_location" text,
  "mens_singles" text,
  "womens_singles" text,
  "mens_doubles" text,
  "womens_doubles" text
);
SELECT "mens_singles" FROM "table1_28138035_27" WHERE "womens_doubles"='Wang Nan Zhang Yining';