The distinction between perfect/imperfective is made clear by using different tenses or phrasings instead:
Séilhetor ag lyfrí foím/foím ag lyfrí - I was reading the newspaper (imperfective)
Séilhetor lyfroí - I read the newspaper (perfective)
adverbs and compound verb forms are used to delineate specific temporal aspects
The active participle of verbs, used to form the antipassive voice, can also convey something like the imperfective aspect.
