Many textbooks of Russian say, quite correctly, that a Russian verb has two stems: the non-past stem and the infinitive/past stem. For example, the verb писать has the non-past stem пиш- (пиш-у, пиш-ешь...пиш-ут) and the infinitive/past stem писа- (писа-ть, писа-л, писа-ла, писа-ло, писа-ли). How do these two stems relate to the concept of the “stem with a full suffix” (the root plus the suffix in its complete form)?
If you know the full-suffix stem, you can find the non-past stem and the infinitive/past stem by applying the rule of likes and unlikes. The infinitive/past stem is simply the full-suffix stem as it would be affected by infinitive/past (i.e., consonant) endings; the non-past stem is the full-suffix stem as it would be affected by non-past (i.e., vowel) endings. If the stem ends in a vowel (for example, пис-а), then infinitive/past endings are simply joined to it without changing it in any way. Since there are no changes, the infinitive/past stem will be identical to the stem with a full suffix:
| писа |
+ |
ть |
= |
писать |
full-suffix stem: |
ПИСА- |
| писа |
+ |
л |
= |
писал |
past/inf stem: |
писа- |
But if you take a vowel stem like писа- and join it to non-past endings, there will be a change because when the two vowels meet, the first of them will drop. In the case of А- stems, the consonant preceding the dropped vowel undergoes a change (see the Consonant Change table):
| писа |
+ |
ут |
= |
пќшут |
говори |
+ |
ят |
= |
говорїт |
||
| full-suffix stem: |
ПИСА- |
full-suffix stem: |
ГОВОРИ- |
||||||||
| non-past stem: |
пиш- |
non-past stem: |
говор(soft)- |
Now let us look at the opposite case, when the stem with a full suffix (for example, читай-) ends in a consonant. Adding non-past (vowel) endings won’t change anything, so that the non-past stem will be identical to the stem with a full suffix:
| читай |
+ |
ут |
= |
читђют |
|
| full-suffix stem: |
ЧИТАЙ- |
||||
| non-past stem: |
читай- |
The infinitive/past endings do change such a stem, because when the two consonants meet, the first of them is dropped. Thus, when a consonant ending is added to читай-, the й drops and you get the infinitive/past stem чита-:
| читай |
+ |
ть |
= |
читђть |
|
| + |
л |
= |
читђл |
||
| full-suffix stem: |
ЧИТАЙ- |
||||
| inf/past stem: |
чита- |
To figure out the infinitive/past or non-past stem from the stem with a full suffix, just apply the rule of likes and unlikes, keeping in mind the special case of ОВА/УЙ verbs. The results are summarized below:
Otherwise
then
The changes described in this section concern the following groups of verbs:
In the first conjugation А stems, when the vowel А is dropped before non-past endings, the consonant preceding the vowel А undergoes changes as predicted in the following table:
| т |
> |
ч |
к |
> |
ч |
п |
> |
пл’ |
| д |
> |
ж |
г |
> |
ж |
б |
> |
бл’ |
| з |
> |
ж |
м |
> |
мл’ |
|||
| с |
> |
ш |
х |
> |
ш |
в |
> |
вл’ |
| ст |
> |
щ |
ск |
> |
щ |
ф |
> |
фл’ |
Examples:
| Infinitive |
Non-past |
||
| пис-ђ-ть |
пќш-ут |
write |
с>ш |
| сказ-ђ-ть |
скђж-ут |
say |
з>ж |
| плак-ђ-ть |
плђч-ут |
cry |
к>ч |
| шепт-ђ-ть |
шљпч-ут |
whisper |
т>ч |
Because of these changes, the non-past stem of an А verb often ends in a consonant that is different from the consonant in the full-suffix stem (identical to the infinitive stem). The changes are predictable.
In И and Е stems the same consonant change occurs only in the first person singular:
| Infinitive |
Non-past |
||
| 3 person Plural |
1 person Singular |
||
| прос-ќ-ть |
прћс-ят |
прош-џ |
с>ш |
| воз-ќ-ть |
вћз-ят |
вож-џ |
з>ж |
| отвљт-и-ть |
отвљт-ят |
отвљч-у |
т>ч |
| верт-љ-ть |
верт-їт |
верч-џ |
т>ч |
| вќд-е-ть |
вќд-ят |
вќж-у |
д>ж |
There are some verbs that depart from the standard set of alternations; their stems end in either -т- or -д-. These consonants normally alternate with -ч- and -ж-, but in such exceptional verbs they alternate with -щ- and -жд, respectively: возвратќть возвращџ Perfective ‘repeat’, возвращђть Imperfective.