Complement Clauses: že and Infinitive Constructions | Czech Grammar

Verbs of saying, thinking, wanting, hoping, and fearing need something to complete them — you don't just think, you think that something is the case; you don't just want, you want to do something or want someone else to do something. English fills that slot in several ways ("I think that he'll come", "I want to go", "I want you to go"). Czech has its own, tidier system built around two devices: a finite že-clause and a bare infinitive — plus a third construction, aby + conditional, that fills a gap English handles with the "want someone to" pattern. Getting these right is mostly about one question: is the subject of the second verb the same as the first, or different?

The default: a finite že-clause with an obligatory comma

The all-purpose complement is a full finite clause introduced by že ("that"). Verbs of saying and thinking take it by default. Two things are non-negotiable: že is almost never dropped the way English drops "that", and there is always a comma before it.

Myslím, že přijde.

I think (that) he'll come. (finite že-clause; comma before že is obligatory)

Řekl, že nemá čas.

He said he had no time. (že-clause; note Czech keeps the present tense 'nemá' where English backshifts to 'had')

Vím, že to umíš.

I know you can do it. (že + full clause with its own subject/verb)

Doufám, že ano.

I hope so. (even a one-word clause keeps že and the comma)

The comma is a hard orthographic rule in Czech: a subordinate clause is fenced off by commas, no exceptions. English speakers, used to omitting "that" and the comma, routinely drop both — and both are errors here.

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Two reflexes to build: never drop že (English drops "that"; Czech keeps it), and always put a comma before it. Myslím, že… — comma, then že. This applies to every subordinate clause, not just complements. See the subordinate-clause page for the wider comma rule.

Same subject → the infinitive

When the subject of the main verb and the subject of the second verb are the same person, many verbs — chtít (want), moci (be able), muset (must), umět (know how), snažit se (try), and others — take a bare infinitive, with no že and no comma. This is the natural equivalent of English "I want to go".

Chci jít.

I want to go. (same subject: I want, I go → infinitive, no že)

Chci spát.

I want to sleep. (bare infinitive)

Nechci tě rušit.

I don't want to disturb you. (same subject 'I'; the object 'tě' is fine — it's still one subject doing the wanting and the disturbing)

Snažím se to pochopit.

I'm trying to understand it. (snažit se + infinitive, same subject)

So chtít has two faces: with the same subject it takes an infinitive, and with a different subject it takes something else entirely — which is the crux of the whole page.

Different subject → aby + conditional (there is no ECM!)

Here is the construction with no English parallel and the deepest source of error. When you want, ask, or arrange for someone else to do something, Czech cannot say "want + object + infinitive" the way English does. English "I want you to go" uses a pattern linguists call ECM (exceptional case marking): the subject of "go" appears as the object of "want". Czech has no such construction. Instead you open a subordinate clause with aby + a special conditional form (abych, abys, aby, abychom, abyste).

Chci, abys šel.

I want you to go. (different subjects: I want, YOU go → aby + conditional 'abys'; NOT 'chci tě jít')

Chci, aby zůstal.

I want him to stay. (aby for a different subject)

Chtěl bych, abyste mi pomohli.

I'd like you to help me. (polite conditional + aby-clause for the different subject)

Compare the two chtít sentences directly and the rule snaps into focus:

Chci jít.

I want to go. (SAME subject → infinitive)

Chci, abys šel.

I want you to go. (DIFFERENT subject → aby + conditional, with a comma)

The forms abych/abys/aby… are the conjunction aby fused with the conditional auxiliary. Their placement and full treatment live on the aby-clause page; here the point is simply that a different subject forces aby, never a bare infinitive with an accusative subject.

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The decision tree for chtít and its relatives: same subject → infinitive (chci jít); different subject → aby + conditional (chci, abys šel). English "want you to go" tempts you into a non-existent Czech pattern — resist it. There is no chci tě jít.

Verbs of asking, telling, and fearing

The same split governs a wider family. Verbs of commanding, requesting, and wishing that someone else do something take aby (or its colloquial cousin ať); verbs of fearing take aby or že depending on what you fear.

Prosím tě, abys mi to nezapomněl.

Please don't forget it for me. (prosit + aby-clause: asking someone else to act)

Řekni mu, ať přijde.

Tell him to come. (colloquial 'ať' + clause — the everyday alternative to aby in commands)

Bojím se, že se to nepovede.

I'm afraid it won't work out. (fear that something WILL happen → že)

Bojím se, aby se mu nic nestalo.

I'm afraid something might happen to him. / I fear for him. (fear lest something happen → aby, often with 'ne')

The bát se že vs bát se aby contrast is subtle: že reports the feared fact plainly; aby (with a negative) expresses the anxious wish that it not occur — closer to archaic English "lest". Both are current; že is the everyday default.

Reporting verbs keep the original tense

One more thing English speakers must unlearn inside že-clauses: Czech does not backshift tenses. English shifts "he has no time" to "he had no time" after a past reporting verb. Czech keeps the tense the speaker originally used.

Řekl, že přijde.

He said he would come. (Czech keeps future 'přijde'; English backshifts to 'would come')

Myslel jsem, že tam jsi.

I thought you were there. (Czech present 'jsi' — the state as it was then; no backshift)

For the finer points of reporting other people's words — including when the conditional shows up — see reported speech with the conditional.

Common Mistakes

❌ Chci tě jít.

Incorrect — Czech has no 'want + object + infinitive' (ECM); a different subject needs aby + conditional.

✅ Chci, abys šel.

I want you to go.

❌ Myslím že přijde.

Incorrect — a comma before 'že' is obligatory.

✅ Myslím, že přijde.

I think he'll come.

❌ Řekl on nemá čas.

Incorrect — the complement of 'řekl' needs the conjunction 'že' (and a comma); you can't just juxtapose two clauses.

✅ Řekl, že nemá čas.

He said he had no time.

❌ Chci, abys jít.

Incorrect — after 'abys' you need a finite (l-participle) form, not an infinitive: abys šel.

✅ Chci, abys šel.

I want you to go.

❌ Řekl, že měl čas. (meaning: he said 'I have time')

Wrong for reporting a present statement — Czech doesn't backshift; keep the present 'nemá/má'.

✅ Řekl, že má čas.

He said he has time.

Key Takeaways

The default complement is a finite že-clause, with že never dropped and an obligatory comma: Myslím, že přijde.
Same subject → infinitive (Chci jít, Snažím se to pochopit).
Different subject → aby + conditional (Chci, abys šel). Czech has no "want + object + infinitive" (ECM) pattern.
Verbs of asking/commanding take aby (or colloquial ať); bát se takes že (feared fact) or aby (anxious wish).
Czech does not backshift tenses in reported speech: Řekl, že přijde = "He said he would come."

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