Aspect with Infinitives in Russian

Overview

When Russian verbs appear in the infinitive -- after modal words, phase verbs, adjectives, or in purpose clauses -- the choice of aspect carries specific meaning. At the B2 level, understanding these patterns is essential because infinitives are extremely common and the aspect choice is not always intuitive from an English perspective.

The general principles still apply (imperfective for process/repetition, perfective for single completed actions), but infinitive contexts introduce additional patterns. Phase verbs (начать, продолжать, закончить) almost always take imperfective infinitives. Modal words (можно, нельзя, нужно) interact with aspect to distinguish between permission/prohibition and possibility/impossibility. Negated infinitives strongly favor the imperfective aspect.

These patterns represent some of the most practical aspect knowledge for intermediate learners, as infinitive constructions appear in nearly every conversation about plans, abilities, obligations, and desires.

How It Works

Phase Verbs: Always Imperfective

Verb	+ Imperfective	Meaning
начать/начинать	начал читать	started reading
продолжать	продолжал работать	continued working
закончить/заканчивать	закончил писать	finished writing
перестать/переставать	перестал курить	stopped smoking

Modal Words: Aspect Changes Meaning

Modal	+ Imperfective	+ Perfective
можно	Можно входить. (You may enter -- permission)	Можно войти? (May I enter? -- single act)
нельзя	Нельзя курить. (Forbidden to smoke)	Нельзя открыть. (Impossible to open)
нужно	Нужно работать. (Need to work -- general)	Нужно сделать. (Need to do -- specific task)

Negated Infinitives: Favor Imperfective

Affirmative (often perf.)	Negative (typically imperf.)
Не забудь позвонить!	Не нужно звонить.
Я решил поехать.	Я решил не ездить.

After Adjectives/Adverbs

Pattern	Example	Aspect
Трудно + inf	Трудно понять. (Hard to understand.)	Either, but perf for specific
Легко + inf	Легко делать ошибки. (Easy to make mistakes.)	Imperf for general
Рано/поздно + inf	Рано вставать. (Too early to get up.)	Imperf for general

Examples in Context

Russian	English	Note
Он начал читать книгу. (process)	He started reading a book.	Phase verb → imperfective
Можно войти? (single action)	May I come in?	Modal + perfective
Я забыл закрыть дверь. (specific)	I forgot to close the door.	Specific past event, perf
Не нужно волноваться. (general)	No need to worry.	Negated → imperfective
Нельзя курить здесь.	No smoking here.	Prohibition, imperf
Нельзя открыть окно.	Can't open the window.	Impossibility, perf
Трудно выучить русский.	It's hard to learn Russian.	General statement
Он продолжал говорить.	He continued speaking.	Phase verb, imperf
Я решил не ехать.	I decided not to go.	Negated decision, imperf
Пора вставать!	Time to get up!	General, imperf

Common Mistakes

Using perfective with phase verbs

• Wrong: Он начал прочитать книгу.
• Right: Он начал читать книгу.
• Why: Phase verbs require imperfective infinitives because they describe the process of an ongoing action.

Not distinguishing можно/нельзя + aspect

• Wrong: Using imperfective/perfective randomly after можно/нельзя
• Right: Imperfective = permission/prohibition; perfective = possibility/impossibility
• Why: The aspect choice fundamentally changes the meaning of the modal construction.

Using perfective in general negated statements

• Wrong: Не нужно сделать это. (specific task framing for a general statement)
• Right: Не нужно делать это. (general advice: no need)
• Why: Negated general advice and prohibitions strongly prefer imperfective infinitives.

Practice Tips

• Practice можно/нельзя + both aspects to internalize the meaning difference: Можно курить? (permission) vs. Можно открыть? (possibility).
• Create sentences with phase verbs + imperfective to build the pattern: начал читать, продолжал работать, перестал курить.

Related Concepts

• Prerequisite: Aspect Usage Rules -- general aspect knowledge before infinitive-specific patterns
• Next steps: Aspect: Advanced Usage -- subtle and context-dependent aspect choices