Aspect After Modal Verbs

Level 4

A modal verb does not decide the aspect. The infinitive after it is imperfective for an activity, a process or a habit (Musím sa učiť) and perfective for one result (Musím to dokončiť do piatku).

How It Works

The modal verbs. musieť (must, have to), môcť (can, may), chcieť (want), mať (be supposed to), smieť (be allowed), and the word treba (it is necessary) are followed by an infinitive. See can and must.

Imperfective infinitive: the activity. Use it for an activity in general, a process that takes time or a habit:

  • Musím sa učiť. I have to study.
  • Chcem celý večer čítať. I want to read all evening.
  • Musíš tam chodiť každý deň? Do you have to go there every day?

Perfective infinitive: one result. Use it for one action that should be completed:

  • Musím to dokončiť do piatku. I have to finish it by Friday.
  • Môžeš mi zavolať po obede? Can you call me after lunch?
  • Chcem sa naučiť plávať. I want to learn to swim. (naučiť sa is the result, plávať is the activity)

A handy test. Duration phrases such as celý deň or dve hodiny go with the imperfective. A deadline such as do piatku or do večera usually goes with the perfective. See imperfective and perfective aspect.

After negative modals.

  • nemôcť + perfective often means you cannot manage a result: Nemôžem nájsť kľúče. (I can't find my keys.)
  • nemusieť + imperfective says an activity is not needed at all: Nemusíš to robiť. (You don't need to do it.) With a perfective it is about one result: Nemusíš to dokončiť dnes. (You don't have to finish it today.)
  • nesmieť forbids. The imperfective states a general rule: Tu nesmieš fajčiť. For one specific act, the perfective is natural too: Nesmieš to nikomu povedať! (You mustn't tell anyone!) See don't have to and must not.

This is different from negative commands, where the imperfective is the normal choice. See aspect in negative commands.

Examples (6)

  1. Musím sa učiť, zajtra píšeme test.

    I have to study; we have a test tomorrow.

    Word by Word: I-must myself study, tomorrow we-write test.

  2. Musím to dokončiť do piatku.

    I have to finish it by Friday.

    Word by Word: I-must it finish by Friday.

    A deadline and one result, so the perfective dokončiť.

  3. Môžeš mi zavolať po obede?

    Can you call me after lunch?

    Word by Word: You-can to-me call after lunch?

  4. Chcem sa naučiť plávať.

    I want to learn to swim.

    Word by Word: I-want myself learn swim.

    Naučiť sa is the result you want. Plávať is the activity itself.

  5. Nemôžem nájsť kľúče.

    I can't find my keys.

    Word by Word: I-cannot find keys.

  6. Tu nesmieš fajčiť.

    You mustn't smoke here.

    Word by Word: Here you-must-not smoke.

    A general rule, so the imperfective fajčiť.

Common Mistakes

  • Using a perfective infinitive with a phrase of duration.

    Chcem celý večer prečítať.
    Chcem celý večer čítať.

    Celý večer (all evening) describes how long an activity lasts, so it needs the imperfective čítať. Prečítať means to read something to the end and needs an object: Chcem prečítať celú knihu.

  • Using the imperfective when you mean getting it done by a deadline.

    Musím ten projekt robiť do piatku.
    Musím ten projekt urobiť do piatku.

    The intended meaning is "I have to get the project done by Friday". Robiť do piatku means to keep working on it until Friday. For a finished result by a deadline, use the perfective urobiť.

  • Putting the modal verb in the infinitive and conjugating the main verb.

    Musieť sa učím.
    Musím sa učiť.

    The modal verb carries the person ending and the main verb stays in the infinitive: musím sa učiť, môžeš prísť, chceme ísť.

How It Connects

Tap a pattern to see what it builds on and what it leads to.

Aspect After Modal VerbsLevel 4

Learn This First

Before Aspect After Modal Verbs, learn Imperfective and Perfective Aspect and Can and Must. Aspect choice applies to infinitives after modal verbs. The rule concerns môcť, musieť and similar verbs.

Words in This Pattern

musieťchcieť