Many Swahili verbs of ability, desire, preference, effort, and memory take a ku- infinitive whose understood actor is the finite verb's subject: Ninaweza kuja “I can come.” Only the first verb carries person and TAM; the infinitive names the controlled action.
English hides this pattern after modal auxiliaries by saying can come, not can to come. Standard Swahili retains infinitival ku- after -weza. Conversely, lazima is not an inflected control verb: it can introduce an impersonal infinitive or a person-marked subjunctive.
Six core builds
| Analytic structure | Finished expression | Meaning |
|---|---|---|
| ni-na-wez-a + ku-j-a | ninaweza kuja | I can come |
| a-na-tak-a + ku-end-a | anataka kwenda | he/she wants to go |
| tu-na-pend-a + ku-pik-a | tunapenda kupika | we like cooking |
| wa-na-jarib-u + ku-elew-a | wanajaribu kuelewa | they are trying to understand |
| a-li-saha-u + ku-fung-a | alisahau kufunga | he/she forgot to close |
| ha-tu-wez-i + ku-subir-i | hatuwezi kusubiri | we cannot wait |
| u-si-saha-u + ku-let-a | usisahau kuleta | do not forget to bring |
| lazima + u-end-e | lazima uende | you must go |
The hyphens expose slots; finished finite verbs and infinitives are each written as one word. In the first seven rows, the finite subject also controls the unspoken subject of the infinitive.
Ninaweza kukutana nawe baada ya saa tisa alasiri.
I can meet you after three in the afternoon.
Hatuwezi kuendelea na mradi bila kibali cha maandishi.
We cannot continue with the project without written authorization.
Affirmative ni-na-wez-a becomes negative-present ha-tu-wez-i with the normal fixed template. The dependent infinitive does not inherit a negative marker.
Taka and penda: desire and preference
Amina anataka kujifunza kutumia programu hiyo mwenyewe.
Amina wants to learn to use that program by herself.
Amina is the understood actor of kujifunza. The finite verb a-na-tak-a supplies current desire, while the infinitive remains tenseless.
Tunapenda kutembea ufukweni jua linapotua.
We like walking on the beach at sunset.
English permits both “like walking” and “like to walk,” sometimes with subtle preferences. Swahili penda + ku- does not reproduce that formal contrast.
Negation can target desire or the desired event:
Hataki kuzungumza na waandishi wa habari leo.
She does not want to speak with journalists today.
Anataka kutotajwa katika taarifa rasmi.
He wants not to be named in the official statement.
The second is structurally possible but relatively marked (formal); everyday speakers often recast it as hataki jina lake litajwe “he does not want his name mentioned.” Scope, not English word order, determines the choice.
Jaribu and sahau: attempted and remembered actions
Dereva alijaribu kuwasha gari mara tatu bila mafanikio.
The driver tried to start the car three times without success.
Trying does not entail success. The infinitive describes the attempted event, and a-li-jarib-u locates the attempt in the past.
Jaribu kuzungumza polepole ili kila mtu akuelewe.
Try to speak slowly so that everyone understands you.
With kusahau, an infinitive normally names an action that should have been remembered.
Nilisahau kuzima taa nilipoondoka ofisini.
I forgot to switch off the light when I left the office.
Usisahau kumtumia mama ujumbe ukifika.
Do not forget to send your mother a message when you arrive.
The human object marker m- belongs inside ku-m-tumi-a. It refers to mama, not to the subject of kusahau.
Lazima is a different construction
Lazima “necessity/must” does not conjugate for the obligated person. When a particular person is obligated, that person is normally marked on a following subjunctive-shaped verb.
Lazima tufike kituoni kabla ya saa kumi na mbili.
We must reach the station before six.
The structure is lazima + tu-fik-e, not tunalazima kufika. In ordinary current usage, a following indicative can occur when necessity is presented as a firm prediction or fact, but lazima + subjunctive is the clearest general obligation pattern.
An infinitive is also standard when the necessity is presented impersonally, without assigning it to a grammatically marked actor:
Ni lazima kuondoka sasa.
It is necessary to leave now.
Compare lazima tuondoke sasa “we must leave now,” which identifies the obligated people through tu-.
Ni lazima wanafunzi wakamilishe usajili leo.
The students must complete registration today.
Because lazima has no controller subject of its own, it is not the same kind of same-subject control verb as kuweza or kutaka. See necessity and obligation.
Same subject versus a new subject
An infinitive normally shares its subject with the controlling verb. If desire or request concerns another actor, Swahili uses a person-marked subjunctive complement.
Nataka kuondoka mapema.
I want to leave early.
Nataka Asha aondoke mapema.
I want Asha to leave early.
In the first, “I” controls kuondoka. In the second, Asha controls a-ondok-e. English uses to leave in both, but Swahili changes construction when the actor changes.
Common Mistakes
Dropping ku- after weza because English drops “to”
❌ Tunaweza maliza leo.
Incorrect in careful Standard Swahili — the complement of weza is infinitival.
✅ Tunaweza kumaliza leo.
We can finish today.
Copying subject and TAM onto both verbs
❌ Ninataka ninaenda nyumbani sasa.
Incorrect for same-subject ‘I want to go’ — the second action should be infinitival.
✅ Ninataka kwenda nyumbani sasa.
I want to go home now.
Keeping affirmative TAM under negation
❌ Hawanaweza kuhudhuria kesho.
Incorrect — negative present of kuweza is hawawezi, without -na-.
✅ Hawawezi kuhudhuria kesho.
They cannot attend tomorrow.
Treating lazima like a conjugated modal
❌ Tunalazima kuondoka kabla ya giza.
Incorrect Standard construction for ‘we must leave.’
✅ Lazima tuondoke kabla ya giza.
We must leave before dark.
Keeping an infinitive when the actor changes
❌ Ninataka Asha kuleta faili hizo.
Incorrect in the ordinary finite complement — Asha requires subject-marked subjunctive alete.
✅ Ninataka Asha alete faili hizo.
I want Asha to bring those files.
Key Takeaways
- Weza, taka, penda, jaribu, and sahau take a ku- infinitive with a shared understood subject.
- Only the finite control verb carries person, TAM, and finite negation.
- Lazima takes a person-marked subjunctive for a specified obligated actor, but an impersonal ni lazima + infinitive is also standard.
- A change of actor also favors an overt noun plus subjunctive form.
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Start learning Swahili →Related Topics
- The Infinitive as a Class-15 NounB1 — Use ku- infinitives as subjects, objects, and predicate expressions, with class-15 agreement and English gerund translations.
- Chains of InfinitivesB1 — Build clear chains in which one finite verb controls successive aspectual, modal, and lexical ku- infinitives.
- Control and Subject Sharing with InfinitivesC1 — Interpret infinitives after modal, aspectual, and intention verbs as sharing a subject, and use finite or subjunctive clauses when a new subject is introduced.
- Necessity and ObligationA2 — Choose lazima, inabidi, yapasa, and negative-possessive budi frames according to subject, tense, force, and register.
- kuweza — Can, Be AbleA1 — Conjugate kuweza with an infinitive to express ability, circumstantial possibility, polite requests, success, and inability.