Russian modals možet 'can' and dolžen 'must' selecting the imperfective in negative contexts

As is well known, there is a strong tendency in the Slavic languages to use the imperfective in negative contexts. However, linguistic mechanisms that lead to a correlation between negation and imperfective are still poorly understood and need further investigation. This paper deals with negation and the imperfective in modal contexts. For example, with the impersonal modal nado ‘‘it is necessary’’, occurring in its primary meaning exclusively with verbs denoting actions (and activities), negation drastically influences the choice of aspect in its dependent infinitive. While in non-negated contexts both aspects are possible, imperfective (ipfv) as well as perfective (pfv), with the ipfv version putting the activity at the center of attention, while with the pfv the focus is transferred to the resulting state. However, in the context of negated nado the only possibility is imperfective. This will be discussed in great detail in the ensuing sections with varying modalities. Section 1 concerns possibility, Section 2 is devoted to necessity. Section 3 deals with disputable examples.