In a method of maintaining temperature of engine exhaust gas from cylinders of a multi-cylinder engine with a desired range, exhaust gas from a first group of cylinders including at least one cylinder is routed to at least one of an EGR system and an exhaust system. If a retrieved content item includes sufficient information for traditional categorization methods, then the system assigns one or more categories to the content item using such traditional methods. A plurality of holes are formed to penetrate the integral package in the vertical direction. Each segment has a hardened crop-engaging face, and the segments are all detachably bolted to the drum of the beater to facilitate removal and replacement when worn or damaged. Because cooling air including the traveling wind can be increased, heat radiation capacity of a radiator disposed in the ventilation duct is improved, and the cooling capacity of the cooling system can also be improved. The additive includes two or more members selected from the group consisting of substances A, B and C, wherein A includes one or more fused ring compounds and fused heterocyclic compounds, B includes an alkoxy aromatic compound, and C includes halogenated borane-based salt.