what date saw the chicago bears lose in green bay earlier than 1931?
CREATE TABLE "1930s_bears_12_11_1" (
  "year" real,
  "date" text,
  "winner" text,
  "result" text,
  "loser" text,
  "attendance" real,
  "location" text
);
SELECT "date" FROM "1930s_bears_12_11_1" WHERE "loser"='chicago bears' AND "location"='green bay' AND "year"<1931;