Irregular Verbs

быть has no present tense in modern Russian. "I am a teacher" is just Я учитель , with no verb. быть shows up in the past (был, была, было, были) and as the auxiliary of the compound future (буду читать).

The past-tense feminine has stress on the ending (была); masculine, neuter, and plural keep the stress on the root (был, было, были). Same stress-shift pattern as пить, жить, ждать; see the past-tense chapter's section on monosyllabic verbs.

хотеть mixes both conjugations, and only this verb does so cleanly. Singular forms use 1st-conjugation endings with a т → ч mutation; plural forms use 2nd-conjugation endings with no mutation. Worth memorising as a unit, since the verb comes up constantly.

Notice the stress shift: я-form is end-stressed (хочу), then the remaining singular forms drop stress to the root (хочешь, хочет), and the plural forms move stress back to the ending (хотим, хотите, хотят). Three stress positions across the paradigm, unusual even for "irregular" verbs.

Two short verbs that conjugate like nothing else. есть uses an athematic pattern in the singular (ем, ешь, ест), no theme vowel between root and ending, and regular endings in the plural. дать is itself perfective and behaves the same way; its imperfective partner is давать (a regular class-13 verb). These two are the modern remnants of an old Indo-European athematic class: Latin has the same pattern in est (is) and dat (gives).

Roughly thirty Russian verbs have infinitives in -чь, which is a phonetic fusion masking an underlying stem in -г- or -к-. In the present tense these stems surface, and they alternate with ж or ч respectively in the middle of the paradigm.

The pattern is: я and они keep the velar (г or к); the middle four forms shift to the husher (ж or ч). This is the same Slavic palatalisation that produced 2nd-conj я-form mutations, but here it operates on an entire paradigm, not a single cell.

The past tense drops -л- in the masculine and surfaces the underlying stem: мочь → мог, могла, могло, могли; печь → пёк, пекла, пекло, пекли; помочь → помог, помогла, помогло, помогли. Other common -чь verbs: лечь (lie down, pf.), беречь (preserve), течь (flow), стричь (cut, of hair), жечь (burn).

About fifteen high-frequency verbs end in stressed -ти. Like the -чь group, the infinitive masks the real stem, most often -с-, -з-, or -д-, which surfaces in the present and past. All are 1st conjugation and end-stressed.

The past also surfaces the real stem and drops -л- in the masculine: нести → нёс, несла, несло, несли; вести → вёл, вела, вело, вели; расти → рос, росла, росло, росли. Other common -ти verbs: идти, везти, цвести, ползти, спасти, пасти. Most describe motion or transport ( Verbs of motion) or growth.

The two foundational verbs of motion are both irregular. They show up so often that learners often meet them before learning the word "irregular". See the Verbs of motion chapter for the full uni/multi system; here we just lay out their present and past paradigms.

The past of идти is fully suppletive: шёл, шла, шло, шли. The present (иду) and the past (шёл) come from two unrelated Indo-European roots that fused into one verb. The past of ехать is regular: ехал, ехала, ехало, ехали. Note also that ехать has no imperative of its own; Russian borrows поезжай, поезжайте from a related verb.