Of the many issues brought up by these two types of passive, it is sometimes proposed that indirect passives are restricted with respect to the base verb they take.
researchers such as Dubinsky (1985Dubinsky ( , 1997, Kageyama (1993Kageyama ( , 1996 and Washio (1989-90) argue for what we refer to as the unaccusative restriction, which bans unaccusatives from appearing as the base verb of the indirect passive.