user: Question: What are the average points of Scuderia Scribante with a Brabham BT11 chassis before 1968?
Columns: ['Year', 'Entrant', 'Chassis', 'Engine', 'Points']
Types: ['real', 'text', 'text', 'text', 'real']
Sample row: [1965.0, 'Ecurie Tomahawk', 'Lotus 20', 'Ford Straight-4', 0.0]
SQL:

assistant: SELECT AVG("Points") FROM "Table" WHERE "Entrant" = 'Scuderia Scribante' AND "Chassis" = 'Brabham BT11' AND "Year" < 1968.0;