Aspect

There are two aspects in Russian - Imperfective and Perfective.

The Imperfective expresses a continuous or repeated action and answers the question "что делать?" (what to do?).

Он сидел и читал.	Не was sitting and reading.
Я всегда читал газету в поезде.	I always used to read the newspaper in the train.

The Perfective stresses the result, or pertains to the end, the completion of an action. It answers the question "что сделать?" (what to have done?).

Она прочитала ваше письмо.

She read (has read) your letter.

Sometimes, the perfective pertains to the beginning of an action:

Ребёнок заплакал.

The child started to cry.

Or it pertains to actions of short duration:

Он чихнул.

Не sneezed.

Also to actions of a longer duration:

Мы погуляли в парке.

We walked (for a while) in the park.

Remarks:

1.  An aspect expresses the nature of an action at the moment it takes place. For instance:

В детстве я много читал.	In my childhood I used to read a lot. (Imperfective: at that moment, the action was not completed or single.)
Я прочитаю это завтра.	I will read this tomorrow. (Perfective: at that moment, the action will be completed.)

2.  The basic correspondence between the principal English and Russian verbal forms is shown in the examples below:

ENGLISH		RUSSIAN
Present Continuous	I am writing	Present	Я пишу
Present	I write	Present	Я пишу
Past Continuous	I was writing	Past Imperfective	Я писал
Past	I wrote	Past Imperfective	Я писал
		Past Perfective	Я написал
Present Perfect	I have written	Past Perfective	Я написал
Past Perfect	I had written	Past Perfective	Я написал
Future Continuous	I will be writing	Future Imperfective	Я буду писать
Future	I will write	Future Imperfective	Я буду писать
		Future Perfective	Я напишу

Notes: 

(a)   The translation of I wrote, I will write and similar expressions depends on the context (imperfective for continuous or repeated actions; perfective for single and completed actions).

(b)   I used to write, etc. is translated by я писал (Imperfective).

(c)   The Present Perfect Continuous and the Past Perfect Continuous are frequently translated with the aid of уже – already.

Я уже давно здесь живу.	I have been living here for a long time.
Я уже давно не был там.	I had not been there for a long time.

Formation of the Aspects

The connection between the aspects of most verbs is usually obvious. However, the formation of one aspect from another varies according to the types listed below, as well as within these types.

Prefixes

Many perfective verbs are formed from the imperfective by adding a prefix:

IMPERFECTIVE		PREFIX	PEREECTIVE
читать	to read	пpo-	прочитать
писать	to write	нa-	написать
делать	to do, to make	c-	сделать
плакать	to cry	за-	заплакать
резать	to cut	раз-	разрезать
ждать	to wait	подо-	подождать
строить	to build	по-	построить
мыть	to wash	вы-	вымыть
красть	to steal	у-	украсть
глохнуть	to grow deaf	о-	оглохнуть

 Remarks:

1.  In addition to these prefixes, there are others which form the so-called "modified perfectives".   In these, the basic meaning is altered:  

IMPERFECTIVE	BASIC PERFECTIVE	MODIFIED PERFECTIVE
писать	написать	переписать   (to copy, to rewrite)
		вписать       (to enter, to write in)
		подписать       (to sign)

Note:   Some prefixed verbs remain imperfective:

(а)   Indefinite verbs of motion, such as ходить which forms the imperfectives приходить – to come; уходить – to leave; входить – to enter, etc.

(b)   A group of verbs with the suffix -ва, such as давать which forms the imperfectives передавать – to hand over, to transmit; отдавать – to give back, to return;   продавать – to sell, etc.

2.   The prefixes пo- and за- impart various meanings to the newly formed perfective verbs.

The prefix пo- expresses:

   (a)   Completion of an action: строить – построить (to build); красить – покрасить (to paint)

Он построил дом.

Не built a house.

   (b)   Doing something for a while; occasionally suggesting a certain informality: гулять – погулять (to walk); говорить – поговорить (to talk)

Я погулял в парке.	I took a walk in the park.
Мы поговорили немного.	We talked for a while.

    (c)   The beginning of an action with Definite (Actual) Verbs of Motion: плыть – поплыть (to swim); ехать – поехать (to go not on foot), etc.

Он поплыл к берегу.

Не started to swim towards the shore.

   (d)   A gradual change: стареть – постареть (to age); худеть – похудеть (to lose weight)

За последнее время он очень постарел.

Lately, he has aged quite a lot.

   (e)   A single action of a short duration:

Он мне позвонил утром.

Не telephoned me in the morning.

Note:  покупать is the imperfective of купить.

  

The prefix за- expresses:

   (a)   The beginning of action:   петь – запеть (to sing);   дрожать – задрожать (to tremble):

Она запела мою любимую песню.

She started to sing my favorite song.

This type, however, is limited to a small number of verbs. Normally, the beginning of an action is expressed with auxiliary verbs:

Он начал работать.	Не has begun to work.
Она стала хорошо учиться.	She is starting to study well.

   (b)   The completion of an action:  мёрзнуть – замёрзнуть (to freeze);  сохнуть – засохнуть (to dry up).

Река замёрзла.

The river has frozen.

Internal Changes

1.   Suffixes -ыва and -ива. With the aid of these suffixes, a modified perfective may form a new imperfective of the same meaning and with the same prefix: переписать – переписывать (to copy); подписать – подписывать (to sign);   достроить – достраивать (to finish building).

In contrast to the above, the basic perfectives (such as написать) as a rule do not form a second imperfective with -ыва or -ива. Exceptions are rare:   читать – прочитать – прочитывать.

 

2.   Suffixes -а, -я and -и.

In any couple of verbs with these suffixes, the one ending in -а(ть) or -я(ть) is the imperfective, the one ending in -и(ть) is the perfective: получать – получить (to receive); решать – решить (to decide); разрешать – разрешить (to allow); выполнять – выполнить (to fulfill). It should not be assumed that the suffix -и alone means that the verb is perfective. The following verbs, for instance, have -и in both aspects:

Imperfective:  говорить – to speak;  курить – to smoke;  пилить – to saw

Perfective:   поговорить, выкурить, распилить

 

3.   The suffix -ва is found in a large group of imperfective verbs:

давать – дать (to give);   вставать – встать (to get up);   узнавать – узнать (to recognize)

and many others where -ва is preceded by да, зна or ста.

The same occurs with prefixed verbs: передавать – передать (to transmit; to give, to hand);   отдавать – отдать (to give back, to return).

 

4.    Suffix -ну

   (a)   The suffix -ну is found in the perfective aspect of a number of verbs: исчезать – исчезнуть (to disappear); толкать – толкнуть (to push);  кричать – крикнуть (to yell).

   (b)   However, when the verb indicates a more gradual, often "involuntary," action, both aspects may have the suffix -ну:   мёрзнуть – замёрзнуть (to freeze);  мокнуть – промокнуть (to get wet);  киснуть – скиснуть (to become sour). This class of verbs expresses a state rather than an action.

 

5.   In addition to these four principal types, there are a large number of verbs which undergo various changes in the stem:

падать – упасть	to fall
спасать – спасти	to save, to rescue
помогать – помочь	to help
предлагать – предложить	to offer, to suggest
начинать – начать	to begin
запирать – запереть	to lock
умирать – умереть	to die
понимать – понять	to understand
собирать – собрать	to gather, to collect

Likewise, the verbs of the same root: занимать – занять (to occupy; to borrow money); выбирать – выбрать (to choose, to elect); убирать –  убрать (to take away; to tidy), etc.

  

6.   Four verbs have the reflexive ending -ся in the imperfective only: ложиться – лечь (to lie down); садиться – сесть (to sit down); становиться – стать (to become);  лопаться – лопнуть (to burst).

 

7.   Читать has two perfectives: прочитать and прочесть. Likewise возвращать(ся) (to return) has возвратить(ся) and вернуть(ся).

Different Roots

In a few instances, the imperfective and perfective aspects have different roots: говорить – сказать (to say); брать – взять (to take); класть – положить (to put).

Change in Stress

Occasionally, the position of the stress changes the aspect. This may take place in the infinitive:

Imperfective: отрезать – to cut off  (Present:   отрезаю, отрезаешь… отрезают)

Perfective: отрезать  (Future:   отрежу, отрежешь… отрежут)

Or, in other tenses:

Present: узнаю, узнаёшь… узнают    (Infinitive: узнавать – to recognize)

Future Perfective: узнаю, узнаешь… узнают  (Infinitive: узнать)

Single Verbs

 Not every verb has two aspects.

   (a) The following verbs occur only in the Imperfective:

заведовать	to manage, to be in charge of
зависеть	to depend
значить	to mean, to signify
иметь	to have
находиться	to be located
недоумевать	to be perplexed, to wonder
нуждаться	to need
обитать	to dwell
обладать	to possess
обожать	to adore
опасаться	to fear
отрицать	to deny
отсутствовать	to be absent
повествовать	to narrate
повиноваться	to obey, to comply (with)
подозревать	to suspect
подражать	to imitate
подразумевать	to imply
покровительствовать	to patronize
предвидеть	to foresee
предчувствовать	to have a premonition, to feel
преследовать	to pursue
принадлежать	to belong
проповедовать	to preach
противоречить	to contradict
разговаривать	to talk
содержать	to contain
сожалеть	to regret
соответствовать	to correspond
состоять	to consist (of)
стоить	to cost
угнетать	to oppress
утверждать	to affirm*

   (b) The following verbs occur only in the Perfective:

заблудиться	to lose one's way*
грянуть	to sound (of thunder)
очнуться	to regain consciousness
очутиться	to find oneself
устоять	to withstand
понадобиться	to be needed
ринуться	to rush
состояться	to take place
стать	to start*
хлынуть	to gush out, to spout, to rush

* The verbs marked with an asterisk do have another aspect but only in a different meaning. Thus, утвердить (perf.) means "to approve (something), заблуждаться (imperf.) - "to err," становиться (imperf.) - "to become".

   (с) The following verbs can be used in either aspect:

велеть	to order		блокировать	to block
обещать	to promise		завещать	to give in will
жениться	to get married		рекомендовать	to recommend
использовать	to use, to make use of		обследовать	to investigate, to inspect
исследовать	to explore, to examine, to study		образовать	to form
казнить	to execute		ранить	to wound, to hurt
миновать	to pass, to elapse; to elude		ремонтировать	to repair, to fix

And many others borrowed from foreign languages:

арестовать	to arrest		ликвидиро­вать	to liquidate
атаковать	to attack		организовать	to organize
конфисковать	to confiscate		деградировать	to degrade

Examples:

Он всегда много обещает, а потом ничего не делает.	Не always promises a lot and then does nothing.   (imperf.)
Если он обещал вам прийти, я уверен, что он придёт.	If he has promised you to come, I am sure he will.   (perf.)
Пока мы атаковали…	While we were attacking…   (imperf.)
Они неожиданно атаковали нас с тыла.	They unexpectedly attacked us from the rear.   (perf.)

Remark: The need for a distinction between two aspects has accounted here for the appearance of another (prefixed) perfective: повелеть; поранить; пожениться; порекомендовать; пообещать, etc.

Через два года они поженились.	Two years later they got married.
Раз он пообещал, наверно, он придёт.	Since he promised, he surely will come.