Some city delivery routes, called curb line routes, use vehicles to provide curbside delivery to a mail receptacle along the curb as is done by rural routes.
In some of the cities, it is illegal to use motorbikes for delivering mail.
mnli hypothesis: In some of the cities, it is illegal to use motorbikes for delivering mail. premise: Some city delivery routes, called curb line routes, use vehicles to provide curbside delivery to a mail receptacle along the curb as is done by rural routes.