Language/Russian/Grammar/Perfective-Imperfective
IMPERFECTIVE ASPECT (Несовершенный вид)
The imperfective may be used in all three tenses in Russian: present, past and future.
The actions must be seen as a process – incomplete, habitual, repetitive, or in general.
Imperfective verbs also refer to actions that take place simultaneously or where there is an interruption.
When in doubt, or if the result is unclear, the imperfective should be used as the default mode.
PERFECTIVE ASPECT (Совершенный вид)
The perfective aspect, by its nature, has only two tenses in Russian: past and future.
Since the present tense is “in progress,” it cannot be completed. Perfective verbs are often used where there was or will be a completed action.
In addition, in questions where the interlocutor specifically asks about an event using the perfective aspect, the same aspect is used in the response.