user: Question: What secondary class of Winter Series champion Andrew Bentley?
Columns: ['Season', 'Champion', 'Constructor', "Teams' Champion", 'Secondary Class', 'Nations Cup', 'Winter Series Champion']
Types: ['text', 'text', 'text', 'text', 'text', 'text', 'text']
Sample row: ['1976', 'David Kennedy', 'Van Diemen', 'Not Held', 'Not Held', 'Not Held', 'Not Held']
SQL:

assistant: SELECT "Secondary Class" FROM "Table" WHERE "Winter Series Champion" = 'Andrew Bentley';