user: Question: How many touchdowns are there when there were 0 extra points and Hal Weeks had Left halfback?
Columns: ['Player', 'Position', 'Starter', 'Touchdowns', 'Extra points', 'Field goals', 'Points']
Types: ['text', 'text', 'text', 'real', 'real', 'real', 'real']
Sample row: ['Tom Hammond', 'Fullback', 'yes', 2.0, 10.0, 0.0, 20.0]
SQL:

assistant: SELECT SUM("Touchdowns") FROM "Table" WHERE "Extra points" = 0.0 AND "Position" = 'Left halfback' AND "Player" = 'Hal Weeks';