短语词组短语elevator ladder dredger 链斗式挖掘机elevator bottom dredger 升降挖泥机elevator r dredger 链斗式挖掘船bucket elevator dredger 链斗式挖泥机bucket dredger elevator dredger 链斗式挖泥船Dredger elevator 梯式戽泥机 返回 elevator dredger