CREATE TABLE table_5291 ("Season" TEXT, "Champion" TEXT, "Constructor" TEXT, "Teams' Champion" TEXT, "Secondary Class" TEXT, "Nations Cup" TEXT, "Winter Series Champion" TEXT)

What secondary class of Winter Series champion Andrew Bentley?
SELECT "Secondary Class" FROM table_5291 WHERE "Winter Series Champion" = 'andrew bentley'
SELECT "Secondary Class" FROM "table_5291" WHERE "Winter Series Champion" = 'andrew bentley'