user: Question: what date saw the Chicago Bears lose in Green Bay earlier than 1931?
Columns: ['Year', 'Date', 'Winner', 'Result', 'Loser', 'Attendance', 'Location']
Types: ['real', 'text', 'text', 'text', 'text', 'real', 'text']
Sample row: [1930.0, 'Sunday, September 28', 'Green Bay Packers', '7–0', 'Chicago Bears', 10000.0, 'Green Bay']
SQL:

assistant: SELECT "Date" FROM "Table" WHERE "Loser" = 'Chicago Bears' AND "Location" = 'Green Bay' AND "Year" < 1931.0;