 "ari" 'is' at the end of a sentence, but "aru-besi" 'has to be').The likelihood is that the monograde verb form used before "tomo" is the earlier true conclusive form, and in Old Japanese this is the only conclusive form attested (always before "tomo"); in Early Middle Japanese the attributive form of monograde verbs came to be used also as a conclusive.With endings such as -"besi", there is strong evidence that they were originally of the form -"ubesi", and that a fusion of the root of the verb with the "u"-sound of the ending, e.g.