FlexiLingoIn one line
Once a question goes inside a sentence it stops being a question: no inversion, no question mark, no
est-ce que.
English has the identical rule and it is one of the first things learners of English are taught. "Where do you live?" becomes "I don't know where you live" — the auxiliary disappears and the subject moves back in front. French does the same thing, which means the instinct is already correct; only the words change.
The table
| Direct question | Inside a sentence |
|---|---|
Où habites-tu ? /u a.bit ty/ | Je ne sais pas où tu habites. /ʒə nə sɛ pa u ty a.bit/ |
Est-ce que tu viens ? /ɛs kə ty vjɛ̃/ | Je ne sais pas si tu viens. /ʒə nə sɛ pa si ty vjɛ̃/ |
Qu'est-ce que tu fais ? /kɛs.kə ty fɛ/ | Je ne sais pas ce que tu fais. /ʒə nə sɛ pa sə kə ty fɛ/ |
Qui vient ? /ki vjɛ̃/ | Je ne sais pas qui vient. /ʒə nə sɛ pa ki vjɛ̃/ |
Three changes
| # | What |
|---|---|
| 1 | the inversion goes — the subject returns in front of the verb |
| 2 | est-ce que disappears — and if it was a yes/no question, si takes its place |
| 3 | no question mark — the sentence is a statement |
The conversion table
| In the direct question | In a sentence |
|---|---|
est-ce que /ɛs kə/ (yes/no) | si /si/ |
qu'est-ce que /kɛs.kə/ | ce que /sə kə/ |
qu'est-ce qui /kɛs ki/ | ce qui /sə ki/ |
où /u/ quand /kɑ̃/ comment /kɔ.mɑ̃/ pourquoi /puʁ.kwa/ qui /ki/ combien /kɔ̃.bjɛ̃/ quel /kɛl/ | unchanged |
Row two and three are the ones with no English parallel. English "what" stays "what" in both — "what are you doing?" / "I don't know what you're doing". French switches to
ce que/ce qui, and forgetting to is the most common error here.
The verbs that take this structure
savoir · demander · dire · comprendre · expliquer · se demander · voir · oublier
Exceptions
| Exception | What happens |
|---|---|
si /si/ here means "whether", not "if" | Je ne sais pas si tu viens. /ʒə nə sɛ pa si ty vjɛ̃/ = I don't know whether you're coming |
si /si/ + il /il/ elides | s'il /sil/ — but si elle /si ɛl/ does not |
A conditional si /si/ never takes a future | but an indirect question does: Je ne sais pas s'il viendra. /ʒə nə sɛ pa sil vjɛ̃.dʁa/ |
| Formal writing sometimes keeps the inversion | Je ne sais pas où est la clé. /ʒə nə sɛ pa.z‿u ɛ la kle/ — allowed with a noun subject |
Examples
| English | French | Pronunciation |
|---|---|---|
| I don't know where you live | Je ne sais pas où tu habites. | /ʒə nə sɛ pa u ty a.bit/ |
| I don't know whether you're coming | Je ne sais pas si tu viens. | /ʒə nə sɛ pa si ty vjɛ̃/ |
| I don't know what you're doing | Je ne sais pas ce que tu fais. | /ʒə nə sɛ pa sə kə ty fɛ/ |
| He asked me when I was leaving | Il m'a demandé quand je partais. | /il ma də.mɑ̃.de kɑ̃ ʒə paʁ.tɛ/ |
| Tell me what time it is | Dis-moi quelle heure il est. | /di mwa kɛ.lœʁ i.lɛ/ |
| I don't understand what's happening | Je ne comprends pas ce qui se passe. | /ʒə nə kɔ̃.pʁɑ̃ pa sə ki sə pas/ |
Common mistakes
| ❌ | ✅ | Why |
|---|---|---|
Je ne sais pas où habites-tu. | Je ne sais pas où tu habites. | The inversion goes |
Je ne sais pas est-ce que tu viens. | Je ne sais pas si tu viens. | est-ce que becomes si |
Je ne sais pas qu'est-ce que tu fais. | Je ne sais pas ce que tu fais. | qu'est-ce que becomes ce que |
Je ne sais pas où tu habites ? | … tu habites. | It is a statement; no question mark |
Je ne sais pas si il vient. | … s'il vient. | si + il elides |
And that si has two meanings
"whether" versus "if" — and how to tell them apart
| Example | si means | How you know | Pronunciation |
|---|---|---|---|
Je ne sais pas si tu viens. | whether | it follows a verb of knowing or asking | /ʒə nə sɛ pa si ty vjɛ̃/ |
Si tu viens, je serai content. | if | it opens the sentence, and the second clause is a result | /si ty vjɛ̃ ʒə sə.ʁe kɔ̃.tɑ̃/ |
And one important grammatical difference:
| Can a future follow? | |
|---|---|
si /si/ = whether | ✅ Je ne sais pas s'il viendra. /ʒə nə sɛ pa sil vjɛ̃.dʁa/ |
si /si/ = if | ❌ Si tu viens /si ty vjɛ̃/ — not viendras /vjɛ̃.dʁa/ |
So if you see a future after si, it must be "whether".
English overloads "if" in exactly the same way — "if it rains, I'll stay in" and "I don't know if he's coming". And English has the same test: if you could substitute "whether", it is the reported-question one. That test works word for word in French — if si could be replaced by "whether" in your English, the future is allowed after it.