In researches carried out on Persian grammar, the category of “exponence” has not been so much a matter of concern, as are the categories of “tense” and “aspect”. The grammatical capacities used for dealing with these three categories, are named “Modals”, which, by definition are formed through the process of modalization of lexical verbs. Modalization is among the general processes of grammaticalization whose grammatical capacities actualize as functional words, clitics, and inflectional affixes. Of all these, functional words and clitics take the position of modals.
This article studies the modals which designate the concept of exponence. The examined categories are among the complete, incomplete, approximate and initial exponences. The examples presented indicate two significant points: first, modal verbs might have various grammatical functions; second, two or more modal verbs might have the same grammatical function.
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