世荣兆业：参股公司玉柴船舶动力股份有限公司的主营业务为生产船用低速发动机

Group 1 - The company, 世荣兆业, primarily engages in real estate development and operation [2] - The company has a stake in 玉柴船舶动力股份有限公司, which specializes in manufacturing marine low-speed engines [2]