нужно/можно/нельзя

Impersonal Predicatives for Necessity and Permission

Level 4Sounds Like nužno/možno/nelʹzâ

Russian uses 'нужно' (need), 'можно' (can/may), and 'нельзя' (must not/cannot) to express modality. These words don't change for person or gender and usually require the person involved to be in the dative case.

How It Works

1. Usage and Meaning
• Нужно / Надо: Expresses necessity. Надо is more common in speech, while нужно is neutral/formal.
• Можно: Expresses permission ('may') or situational possibility ('can').
• Нельзя: Its meaning depends heavily on verbal aspect:
  - With Imperfective: Prohibition ('It is forbidden').
  - With Perfective: Impossibility ('It is impossible to succeed').

2. Sentence Structure
The structure is: [Dative Person] + [Predicative] + [Infinitive].
• Мне нужно идти. (I need to go.)
• Вам можно войти. (You may enter.)

3. Tense Changes
Since these forms are frozen, tense is shown using the neuter singular form of the verb 'to be':
• Past: нужно было / можно было / нельзя было.
• Future: нужно будет / можно будет / нельзя будет.

4. Nuances
Do not confuse нужно (used with verbs) with the short adjective нужен/нужна/нужны (used with nouns). Also, нельзя (forbidden) differs from не надо (not necessary/don't do that).

Examples (5)

  1. Тебе нужно больше отдыхать.

    You need to rest more.

    Word by Word: To-you necessary more to-rest.

    Uses the dative 'тебе' and the imperfective infinitive to express a general necessity.

  2. Здесь нельзя курить.

    Smoking is forbidden here.

    Word by Word: Here forbidden to-smoke.

    When 'нельзя' is paired with an imperfective verb (курить), it indicates a prohibition or rule.

  3. Эту задачу нельзя решить быстро.

    It is impossible to solve this problem quickly.

    Word by Word: This task impossible to-solve quickly.

    When 'нельзя' is paired with a perfective verb (решить), it indicates physical or logical impossibility.

  4. Нам можно было пользоваться словарём.

    We were allowed to use a dictionary.

    Word by Word: To-us possible was to-use dictionary.

    Shows the past tense using the neuter 'было' and the instrumental case after 'пользоваться'.

  5. Вам не надо так волноваться.

    You shouldn't worry so much.

    Word by Word: To-you not necessary so to-worry.

    'Не надо' is used here for advice or to say something is unnecessary, rather than strictly forbidden.

Common Mistakes

  • Using the nominative case for the person who 'needs' or 'can'.

    Я нужно работать.
    Мне нужно работать.

    Impersonal predicatives require the experiencer to be in the dative case (мне, тебе, ему, etc.), not the nominative (я, ты, он).

  • Using the wrong gender for the auxiliary verb 'быть' in the past tense.

    Книга нужно была мне.
    Мне нужно было купить книгу.

    When used with an infinitive, the past tense auxiliary must always be the neuter 'было', regardless of the gender of other nouns in the sentence.

  • Using a perfective verb with 'нельзя' to express a rule.

    Здесь нельзя прийти.
    Сюда нельзя входить.

    To express that an action is forbidden by rule or law, you must use the imperfective aspect. Using the perfective implies the action is physically impossible to complete.

How It Connects

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нужно/можно/нельзяLevel 4Impersonal Predicatives for Necessity and Permission

Learn This First

To learn 'нужно/можно/нельзя', you need to understand how to form the dative case for the person involved (the experiencer) and how to use the infinitive to specify the action. It is also helpful to understand the concept of short-form adjectives, as these words function as impersonal predicates.

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Words in This Pattern

нужноможнонельзя