The affix liṅ (Benedictive) comes after a verb in all tenses when the words uta and api , both having the same meaning, are in composition. ,
This excludes all the other tense-affixes. The meaning which is common both to उत and अपि is that of बाढम् 'assuredly, certainly, surely, really'. Thus उत कुर्यात् 'certainly he does'; अपि कुर्यात् 'assuredly he does' उताधीयीत 'certainly he studies (will study &c)'; अप्यधीयीत 'surely he studies &c'.
Why do we say 'when they mean certainly'? Observe उत दण्डः पतिष्यति 'will the stick fall'? अपि द्वारं धास्यति 'he shuts the door'. Here उत is employed in asking questions, and अपि with धा means 'to shut'. The option allowed by rule (III. 3. 141.) ceases. Hereafter the Conditional (लृङ्) must invariably be used even in indicating Past action, when action is not completed, and there is reason for the employment of लिङ्(Potential). In indicating Future time, of course, लङ् must necessarily be employed as before. Henceforward, therefore, no option is allowed, but लृङ् must be employed where sutras 3.3.139 and 3.3.140 require it.,