An indirect question embeds a question as part of a larger sentence: Mi ne scias, ĉu ŝi venos “I don't know whether she will come” or Diru al mi, kie vi loĝas “Tell me where you live.” Esperanto uses ĉu for embedded yes-no questions and the appropriate ki-correlative for embedded content questions. It does not use English inversion, question-forming do, or ke “that” to introduce the embedded question.
Two embedded patterns
The form depends on the answer the embedded question seeks.
| Missing answer | Introducer | Example |
|---|---|---|
| yes or no | ĉu | Mi ne scias, ĉu ŝi venos. |
| person, thing, place, time, reason, manner, quantity | appropriate ki- word | Mi ne scias, kiam ŝi venos. |
Compare the direct question and its embedded version:
Ĉu la trajno jam alvenis?
Has the train arrived yet?
Mi ne scias, ĉu la trajno jam alvenis.
I don't know whether the train has arrived yet.
Kiam la trajno alvenos?
When will the train arrive?
Ĉu vi scias, kiam la trajno alvenos?
Do you know when the train will arrive?
The internal order la trajno alvenos stays the same. Esperanto does not alternate between English-style when will the train arrive? and when the train will arrive. The ki-phrase begins its own clause in both cases, and no inversion occurs in either.
Embedded yes-no questions use ĉu, not ke
Ke introduces reported statements and other declarative content. Ĉu introduces an unresolved yes-no issue.
Ŝi diris, ke la pordo estas ŝlosita.
She said that the door is locked.
Ŝi demandis, ĉu la pordo estas ŝlosita.
She asked whether the door is locked.
The first presents “the door is locked” as the content of a statement. The second presents “is the door locked?” as a question whose truth is unresolved. This semantic difference—not the preceding verb alone—chooses ke or ĉu.
Ni ankoraŭ diskutas, ĉu ni renovigu la malnovan retejon.
We are still discussing whether we should redesign the old website.
La demando estas, ĉu ĉiuj ricevis la invitilon.
The question is whether everyone received the invitation.
An embedded question can be the object of a verb, a description of a noun, a predicative complement, or even the subject-like content under discussion. It is not restricted to demandi “ask.” Common frames include scii, ne scii, dubi, kontroli, decidi, pripensi, and klarigi.
Ĉu and se are not interchangeable
English if can introduce either an indirect question or a condition. Esperanto keeps these meanings separate. Ĉu means “whether”; se means “if, on condition that.”
Morgaŭ li diros, ĉu li venos.
Tomorrow he will say whether he is coming.
Morgaŭ li diros ion, se li venos.
Tomorrow he will say something if he comes.
In the first, the future statement supplies a yes-or-no answer. In the second, his coming is the condition under which he will say something. This is a foundational normative distinction in Esperanto.
Embedded content questions keep the ki-word
Use the same ki-correlative that would introduce the direct question. It keeps its role inside the embedded clause.
Mi volas ekscii, kiu lasis ĉi tiun mesaĝon.
I want to find out who left this message.
Ĉu vi memoras, kiun ni renkontis ĉe la kongreso?
Do you remember whom we met at the convention?
Bonvolu klarigi, kial la pago estis rifuzita.
Please explain why the payment was declined.
Neniu sciis, kiom da homoj ankoraŭ atendis ekstere.
Nobody knew how many people were still waiting outside.
The object form kiun remains accusative because it is the object of renkontis, not because of the main verb memoras. Likewise kiom da homoj supplies the subject of atendis.
Prepositions stay with the embedded question phrase:
Mi ne scias, kun kiu ŝi parolis post la kunveno.
I don't know who she spoke with after the meeting.
Ni devas decidi, ĝis kiam la aliĝilo restos malfermita.
We have to decide until when the registration form will remain open.
The whole phrases kun kiu and ĝis kiam begin their embedded clauses. English preposition stranding does not transfer.
Punctuation depends on the whole sentence
An embedded question does not automatically make the whole sentence a direct question. Use a question mark only when the main sentence itself asks the reader or listener something.
Mi ne scias, kie Lea lasis la ŝlosilojn.
I don't know where Lea left the keys.
Ĉu vi scias, kie Lea lasis la ŝlosilojn?
Do you know where Lea left the keys?
Diru al mi, kie Lea lasis la ŝlosilojn.
Tell me where Lea left the keys.
The first is a statement and ends with a period. The second is a direct yes-no question because of the main-clause ĉu. The third is a request with a volitive verb; it is not grammatically a direct question even though it seeks information.
In ordinary written Esperanto, a comma commonly separates the main clause from the following subordinate question, as in the examples above.
Negation and scope
Negation can belong to the main clause, the embedded clause, or both. Position tells the reader which proposition is denied.
Mi ne scias, ĉu ili jam foriris.
I don't know whether they have already left.
Mi scias, ke ili ne foriris.
I know that they did not leave.
Mi ne scias, kial neniu respondis.
I don't know why nobody answered.
In the first, ne denies knowing; it does not say that they stayed. In the second, ne is inside declarative content and denies leaving. In the third, neniu supplies the embedded clause's negative meaning. A NENI- form normally negates the whole clause; adding ne normally reverses that negative, whereas several NENI- forms can sometimes reinforce one negation. Read each form by its scope rather than transferring an English double-negative rule.
Tense in reported questions
Esperanto does not apply automatic English-style sequence-of-tense backshift. Preserve the verb form appropriate to the original viewpoint.
Ŝi demandis: ‘Ĉu vi venos morgaŭ?’
She asked: ‘Will you come tomorrow?’
Ŝi demandis, ĉu mi venos la sekvan tagon.
She asked whether I would come the next day.
English changes will to would. Esperanto keeps future -os, because the visit was future from the original questioner's viewpoint. Pronouns and time expressions may change—vi to mi, morgaŭ to la sekvan tagon—but the verb ending is not mechanically shifted.
Li demandis, kie mi loĝas.
He asked where I lived at that time.
Here loĝas preserves an original Kie vi loĝas? It does not necessarily claim that the residence is still current now. See relative time without backshift for the full system.
Indirect questions versus relative clauses
A ki-clause can sometimes look like a relative clause. Meaning distinguishes them. An indirect question denotes the issue or its answer; a relative clause identifies a thing.
Ŝi klarigis, kion la raporto enhavas.
She explained what the report contains.
This can mean that she supplied the answer to “What does the report contain?” In a suitable context, a similar form can refer to the actual material that the report contains. At B1, the practical test is to ask whether a real underlying question can be reconstructed. If yes, the clause is interrogative.
Register and variation
The ĉu/ki- distinction is foundational standard Esperanto across registers. Full embedded clauses are neutral in speech and writing. Traditional usage often places pri tio before a question clause when a governing expression requires pri:
Ni parolis pri tio, ĉu la propono estas realisma.
We talked about whether the proposal is realistic.
Direct pri kiel, pri kial, pri kie without tio is also increasingly common and accepted when clear, especially with adverb-like ki-words. With ĉu, kio, kiu, or kia, pri tio, … generally prevents a momentary attachment ambiguity and remains the safest pedagogical choice.
Common Mistakes
1. Using ke for an unresolved yes-no question.
❌ Mi ne scias, ke ŝi venos.
Incorrect for ‘I don't know whether she will come’ — ke presents a statement, not a question.
✅ Mi ne scias, ĉu ŝi venos.
I don't know whether she will come.
2. Using se as English ‘if’ meaning ‘whether.’
❌ Mi ne scias, se ŝi alvenos ĝustatempe.
Incorrect for ‘I don't know whether she will arrive on time’ — se introduces a condition, not an embedded question.
✅ Mi ne scias, ĉu ŝi alvenos ĝustatempe.
I don't know whether she will arrive on time.
3. Combining ĉu with a ki-word in the same embedded clause.
❌ Mi ne scias, ĉu kie ili loĝas.
Incorrect — kie already introduces the embedded content question.
✅ Mi ne scias, kie ili loĝas.
I don't know where they live.
4. Copying English inversion or do-support.
❌ Ŝi demandis, kie faras li loĝi.
Incorrect — faras cannot reproduce English question-forming ‘does.’
✅ Ŝi demandis, kie li loĝas.
She asked where he lived.
5. Backshifting future -os to conditional -us.
❌ Ŝi demandis, ĉu mi venus morgaŭ.
Incorrect if her original question was a real future ‘Will you come tomorrow?’
✅ Ŝi demandis, ĉu mi alvenos la sekvan tagon.
She asked whether I would arrive the next day.
-Us is correct only when the original meaning was genuinely hypothetical, not merely because English uses would in reported speech.
Key Takeaways
Embed a yes-no issue with ĉu and a content issue with the same ki-correlative used in the corresponding direct question. Keep normal Esperanto clause order, retain case and prepositions inside the embedded clause, distinguish interrogative ĉu from conditional se, and preserve the intended tense instead of copying English backshift.
Related Topics
- Yes-No Questions with ĈuA1 — Form yes-no questions with ĉu while keeping normal clause order, clear negation, and unambiguous answers.
- Content Questions with Ki-CorrelativesA1 — Ask for people, things, qualities, places, times, reasons, manners, and quantities with Esperanto's systematic ki-correlatives.
- Ĉu-Clauses as Embedded QuestionsA2 — How ĉu introduces a finite yes/no question functioning inside a larger sentence, distinct from ke statements and se conditions.
- Ki-Correlative Embedded QuestionsB1 — How kiu, kio, kia, kies, kie, kiam, kial, kiel, and kiom introduce finite questions embedded inside larger clauses.
- Reported QuestionsB2 — Embed yes-no and content questions with ĉu or a ki-correlative while preserving finite clause structure, tense, case, and viewpoint.
- Relative Time without Sequence-of-Tense BackshiftA2 — Preserve the original verb form in reported speech and thought instead of applying English-style tense backshift.