ten, kdo / to, co

Free Relative Kdo and Co

Level 3

Use ten, kdo (the one who / whoever) for people and to, co (that which / what) for things when there is no specific noun being referred to.

How It Works

When you want to say 'whoever' or 'what' in a sentence like 'I like what you said', Czech uses a two-part structure: a demonstrative pronoun in the main clause and a relative pronoun in the dependent clause.

1. People vs. Things

  • Ten, kdo... refers to a generic person (the one who, whoever, anyone who). The verb after kdo takes masculine animate singular agreement here. While ten, kdo is the default generic form, note that combining the feminine demonstrative with kdo (ta, kdo) is traditionally considered prescriptively incorrect, and you should generally use ta, která when specifically identifying a female subject. However, in modern Czech, ta, kdo is sometimes used for emphatic identification (e.g., Ona je ta, kdo rozhoduje).
  • Ti, kdo... refers to a generic group of people (those who). When following the plural antecedent ti, the verb in the relative clause takes plural agreement (e.g., Ti, kdo přišli... = Those who came...).
  • To, co... refers to a generic thing or abstract concept (that which, what). Note that co always takes neuter singular verb agreement (e.g., To, co se stalo... = What happened...).

2. Independent Declension
This is not a fixed phrase! The two pronouns decline independently. Remember that kdo and co decline like nouns (e.g., koho, komu, kým / čeho, čemu, čím). For example, in Dej to tomu, kdo přijde první (Give it to whoever comes first):

  • tomu is in the dative case because it is the indirect object of 'give' in the main clause.
  • kdo is in the nominative case because it is the subject of 'comes' in the subordinate clause.

Conversely, the relative pronoun can also change case depending on its role in the dependent clause. For example, in Dělám to, čemu věřím (I do what I believe):

  • to is in the accusative case as the direct object of 'do'.
  • čemu is in the dative case because the verb 'believe' requires it.

3. Kdo/Co vs. Který
Use který when referring back to a specific noun (e.g., muž, který... = the man who...). Use kdo/co when there is no noun antecedent (e.g., ten, kdo... = the one who...). Additionally, co is the required relative pronoun after indefinite pronouns like všechno (everything) and nic (nothing), e.g., Všechno, co chci... (Everything that I want...).

Note: While using co instead of který after a noun is colloquial, the headless to, co construction is fully standard, formal, and register-neutral.

Examples (5)

  1. Ten, kdo to udělal, se musí přiznat.

    Whoever did it must confess.

    Word by Word: That (one), who it did, himself must confess.

    Both pronouns are in the nominative case because they are the subjects of their respective clauses.

  2. To, co jsi řekl, mě zklamalo.

    What you said disappointed me.

    Word by Word: That, what you said, me disappointed.

    'To' is nominative (subject of disappointed), while 'co' is accusative (object of said).

  3. Dej to tomu, kdo přijde první.

    Give it to whoever comes first.

    Word by Word: Give it to that (one), who comes first.

    'Tomu' is dative (indirect object of give), but 'kdo' is nominative (subject of comes).

  4. Vážíme si toho, co pro nás děláte.

    We appreciate what you are doing for us.

    Word by Word: We appreciate of that, what for us you do.

    'Toho' is genitive (required by the verb vážit si), while 'co' is accusative (object of děláte).

  5. Mluvili jsme o tom, koho jsme včera potkali.

    We talked about the person we met yesterday.

    Word by Word: We talked about that (one), whom we yesterday met.

    'Tom' is locative (after the preposition o), and 'koho' is accusative (object of potkali).

Common Mistakes

  • Forcing both pronouns into the same case (Case Attraction).

    Dej to tomu, komu přijde první.
    Dej to tomu, kdo přijde první.

    Because English 'the one who' feels like a single unit, learners often mistakenly match the cases. The pronouns must decline independently based on their role in their own clause. 'Kdo' is the subject of 'přijde', so it must be nominative, even though 'tomu' is dative.

  • Using 'kdo' or 'co' directly after a specific noun.

    To je ten člověk, kdo mi pomohl.
    To je ten člověk, který mi pomohl.

    When there is a specific noun antecedent (like 'člověk'), you must use the relative pronoun který. Use 'kdo' only when there is no noun (e.g., 'To je ten, kdo mi pomohl').

  • Forgetting the mandatory comma.

    To je to co chci.
    To je to, co chci.

    Czech punctuation rules strictly require a comma before the relative clause starting with 'kdo' or 'co'.

How It Connects

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ten, kdo / to, coLevel 3Free Relative Kdo and Co

Learn This First

To understand free relative clauses like 'ten, kdo' or 'to, co', a learner must first be familiar with the demonstrative pronoun 'ten' and the basic interrogative pronouns 'kdo' and 'co'. Furthermore, since these pronouns often change case depending on the verb in the relative clause (e.g., 'to, co vidím'), knowledge of their declension is essential.

Words in This Pattern

tenco