A complex sentence in Ukrainian is a main clause plus one or more subordinate clauses, each hooked on by a conjunction or relativizer and walled off by a comma. Two facts make the Ukrainian system tidier than the English one — and two facts make it trickier. Tidier: the connector is never dropped (you cannot omit "that" the way English does), and the boundary is always comma-marked. Trickier: the type of clause dictates the verb form inside it — a future after time/condition conjunctions pointing at the future, a past + the particle би after якби, a bare past after щоб when the subjects differ. This page is the overview that ties the conjunction pages, the conditional page, and the relative-clause page together into one map.
Complement clauses: що, чи, щоб
A complement clause fills an argument slot of the main verb — it is what you know, say, think, or ask. The three workhorse connectors are що "that," чи "whether/if," and щоб "that (someone should)."
- що — after verbs of saying, knowing, thinking, feeling: a statement of fact
- чи — after verbs of asking, knowing, doubting: an embedded yes/no question
- щоб — after verbs of wanting, asking, demanding: a desired, non-factual content
Я зна́ю, що він уже́ поверну́вся з відря́дження.
I know that he's already back from his business trip.
Не впе́внений, чи всти́гну на оста́нній авто́бус.
I'm not sure whether I'll make the last bus.
Мама́ хо́че, щоб ми поверну́лися до десяти́.
Mum wants us to be back by ten.
The split between що and щоб is the first thing to fix: що introduces a fact (with an ordinary indicative verb), while щоб introduces a wished-for content and, crucially, takes a past-tense form when the subjects differ (хо́че, щоб ми поверну́лися) — the closest Ukrainian has to a subjunctive.
Relative clauses: який, що, котрий
A relative clause modifies a noun, telling you which one. The relativizers are який (agreeing in gender, number and case), the invariant що, and the more formal котрий — covered in full on the relative-clause page.
Це той фільм, про який усі́ говоря́ть.
This is the film that everyone is talking about.
Жі́нка, що сиди́ть біля вікна́, — моя́ вчи́телька.
The woman who's sitting by the window is my teacher.
The relativizer is never dropped: English freely says "the film everyone's talking about," but Ukrainian must keep який/що and set the clause off with commas on both sides if it is medial.
Adverbial clauses: time, cause, purpose, condition, concession
The largest family is adverbial — clauses that answer when, why, what for, on what condition, or despite what. Each type has its own conjunction(s), and several of them govern a specific verb form.
| Type | Conjunctions | Verb-form note |
|---|---|---|
| Time | коли́, поки́, як ті́льки, доки́, пі́сля то́го як | future for future reference (Коли́ прийде́ш…) |
| Cause | бо, тому́ що, оскі́льки, че́рез те що | indicative |
| Purpose | щоб, для то́го щоб, аби́ | past form if subjects differ; infinitive if same |
| Condition | якщо́, якби́, коли́ б | якщо́ + future (real); якби́ + past + би (unreal) |
| Concession | хоч, хоча́, дарма́ що, попри те що | indicative |
| Result | так що, тому́ | indicative |
| Manner/comparison | як, ні́би, на́че, мов | indicative |
Time — and the future-tense trap
After time conjunctions pointing at the future, Ukrainian uses the future tense where English keeps the present. "When you arrive, call me" → Ukrainian Коли́ прийде́ш, подзвони́ (future прийде́ш, not present).
Коли́ прийде́ш додо́му, одра́зу подзвони́ мені́.
When you get home, call me right away.
Поки́ дощ не зака́нчиться, поси́димо в кав’я́рні.
Until the rain stops, we'll sit in the café.
Cause and concession
Cause clauses (бо, тому́ що, оскі́льки) and concession clauses (хоч, хоча́) keep the plain indicative — no special form, just the conjunction and comma.
Я не пішо́в на робо́ту, бо захворі́в.
I didn't go to work because I fell ill.
Хоч було́ пі́зно, ми вирі́шили піти́ пішки́.
Although it was late, we decided to walk.
Purpose — щоб with two patterns
Purpose clauses with щоб split by subject. Same subject as the main clause → щоб + infinitive. Different subject → щоб + past-tense form (the pseudo-subjunctive).
Я встав ра́но, щоб усти́гнути на по́тяг.
I got up early in order to catch the train. (same subject → infinitive)
Я встав ра́но, щоб ді́ти не запізни́лися до шко́ли.
I got up early so that the children wouldn't be late for school. (different subject → past form запізни́лися)
Condition — якщо́ (real) vs якби́ (unreal)
The condition clauses are where the verb form matters most, and they have a dedicated page (conditional sentences, якщо vs якби). Real/likely condition → якщо́ + future. Unreal/hypothetical → якби́ + past + the particle би/б in both clauses.
Якщо́ за́втра не бу́де дощу́, пої́демо за мі́сто.
If it doesn't rain tomorrow, we'll go out of town. (real → якщо́ + future)
Якби́ я знав про це ра́ніше, я б учини́в інакше.
If I'd known about it earlier, I would have acted differently. (unreal → якби́ + past + би)
The comma rule
The boundary between clauses is always marked with a comma — before the conjunction in most adverbials (…, бо…; …, коли́…), on both sides of a medial relative or complement clause, and before що / чи / щоб without exception. Multi-word conjunctions (тому́ що, для то́го щоб) are usually written whole inside the comma, though a contrastive reading can split them (…саме тому́, що…). When in doubt: if there is a subordinate clause, there is a comma.
Source-language comparison
For an English speaker, two habits must change. First, never drop the connector: English "I think he's right" and "the book I read" both delete the relativizer/complementizer, but Ukrainian requires Я ду́маю, що він ма́є ра́цію and кни́жка, яку́ я прочита́в. Second, switch the tense after time/condition conjunctions: English says "when you arrive (present)," Ukrainian says Коли́ прийде́ш (future). Forgetting the future here is the single most common B1–B2 error. The щоб split (infinitive for same subject, past form for different subject) and the якщо́/якби́ split (future vs past + би) are the two pairs worth drilling until automatic.
For a Russian speaker, the system maps closely (что/що, чтобы/щоб, если/якщо́, если бы/якби́), but the lexical conjunctions differ enough to trip you: Ukrainian бо "because" (no Russian cognate), оскі́льки "since," хоч / дарма́ що "although," попри те що "despite the fact that." And якби́ folds the conditional particle into one word, where Russian keeps если бы separate.
Common Mistakes
❌ Я зна́ю він прийде́.
The connector is missing — Ukrainian never drops що: Я зна́ю, що він прийде́.
✅ Я зна́ю, що він прийде́.
I know that he'll come — obligatory що and comma.
❌ Коли́ ти прихо́диш додо́му, подзвони́ мені́.
Wrong tense for future reference — use the future after коли́: Коли́ прийде́ш додо́му, подзвони́.
✅ Коли́ прийде́ш додо́му, подзвони́ мені́.
When you get home, call me — future прийде́ш, not present.
❌ Якби́ я зна́ю про це, я б прийшо́в.
якби́ requires the past + би, not the present: Якби́ я знав про це, я б прийшо́в.
✅ Якби́ я знав про це, я б прийшо́в.
If I'd known about it, I'd have come — якби́ + past + би.
❌ Мама́ хо́че, щоб ми поверта́ємося до десяти́.
After щоб with a different subject use the past form, not the present: Мама́ хо́че, щоб ми поверну́лися до десяти́.
✅ Мама́ хо́че, щоб ми поверну́лися до десяти́.
Mum wants us to be back by ten — щоб + past form.
Key Takeaways
- Every subordinate clause is overtly introduced (the connector is never dropped) and comma-marked.
- Complement: що 'that' (fact), чи 'whether' (embedded question), щоб 'that (wished)'.
- Relative: який (agreeing), що (invariant), котрий (formal) — also never dropped.
- Adverbial: time (коли́ + future), cause (бо, тому́ що), purpose (щоб + infinitive or past form), condition (якщо́ + future / якби́ + past + би), concession (хоч, хоча́).
- The clause type dictates the verb form — get the future after коли́, the past + би after якби́, and the past form after щоб with a different subject.
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- Subordinating Conjunctions: Time and CauseA2 — The subordinators that attach a when-clause or a why-clause, each with an OBLIGATORY comma before it. Time: коли́ 'when' (future after коли́ for future reference — Коли́ закі́нчу, відпочи́ну, both future!), по́ки/до́ки 'while/until', як ті́льки 'as soon as', пі́сля то́го як 'after', перш ніж / пе́ред тим як 'before', відто́ді як 'since'. Cause: бо 'because' (everyday, never starts a sentence), тому́ що (slightly more formal), оскі́льки 'since', че́рез те що, завдяки́ тому́ що 'thanks to'; тому́ alone = 'therefore'.
- Subordinating Conjunctions: Condition, Purpose, ConcessionB1 — Three families of subordinators that English collapses or marks only with verb forms. CONDITION: якщо́ 'if' for real/likely conditions (with the FUTURE — Якщо́ бу́де дощ, залиши́мося вдо́ма) versus якби́ 'if' for hypotheticals (with PAST + би/б — Якби́ був дощ, ми б залиши́лися). PURPOSE: щоб 'so that / in order to', + infinitive for the same subject, + past form for a different subject; also для то́го щоб, аби́. CONCESSION: хоч/хоча́ 'although', незважа́ючи на те що 'despite', дарма́ що, хай/нехай 'even if'. Comma before the subordinator.
- Conditional Sentences (Real and Unreal)B1 — Ukrainian splits 'if'-sentences into just two patterns where English has three or more. REAL conditions use якщо́ + the indicative (typically the FUTURE in BOTH clauses): Якщо́ бу́де дощ, ми залиши́мося вдо́ма. UNREAL/hypothetical conditions use якби́ + the past form, with би/б in BOTH clauses: Якби́ я був бага́тий, я б подорожува́в — and this single form covers BOTH 'if I were' (present-unreal) and 'if I had been' (past-unreal); context and aspect tell them apart. There is no separate 'would have'.
- Relative Clauses (Який, Що, Хто)B1 — How Ukrainian builds 'the house we saw,' 'the woman I spoke with,' 'the city I was born in.' The relativizer який agrees with its antecedent in gender and number but takes its CASE from its role inside the relative clause, so one word points two ways at once; the comma before it is obligatory; prepositions front (з якою, в якому) and are never stranded; the invariant що is the colloquial subject/object option; and той, хто / те, що build headless relatives.
- Якщо vs Якби ('if')B1 — The decision page for Ukrainian's two 'if' conjunctions. Якщо́ = a REAL/open condition with the indicative (usually future): Якщо́ ти при́йдеш, ми пого́воримо. Якби́ = an UNREAL/counterfactual condition with the particle би/б in BOTH clauses: Якби́ я мав час, я б прийшо́в. Plus the чи warning for indirect 'whether' — English 'if' covers all three.
- Compound and Complex SentencesA2 — How clauses join. A SIMPLE sentence is one clause; a COMPOUND sentence (складносуря́дне) links clauses of equal rank with і, а, але́, або́, та; a COMPLEX sentence (складнопідря́дне) hangs a subordinate clause off a main one with що, щоб, коли́, бо, якщо́, який. The comma before every subordinator and relativizer is OBLIGATORY — unlike English's optional 'that' — and the complement що is never dropped the way English drops it ('I know you're right' must be Я зна́ю, що ти ма́єш рацію).