IB Diploma Spanish B HL · Grammar backbone 8 of 10 — Infinitive & participle constructions
IB Spanish B · HL
Infinitive & participle constructions
Once you leave single verbs behind, Spanish strings verbs together in fixed patterns. Some verbs take an infinitive directly; others demand a preposition first. Then there is al + infinitive, the gerund (-ando/-iendo), and the rule that trips up every English speaker: Spanish uses the infinitive, not the gerund, as a noun. In IB Diploma Spanish B HL, this grammar powers your work across the five prescribed themes — Identities, Experiences, Human ingenuity, Social organization and Sharing the planet — and the two literary works you study, especially when you recount your Experiences.
verb + (prep?) + infinitivequiero ir · empiezo a trabajar · acabo de comer
Work through each screen and answer the questions — some ask you to recognise the pattern, some to produce it. Collect ⭐ and press Start.
Pattern 1
Verb + infinitive (no preposition)
A core group of verbs is followed by the infinitive directly — nothing in between. These are your everyday modal-style verbs:
quiero ir — I want to go
puedo hacer — I can do
debo estudiar — I must study
prefiero salir — I prefer to go out
The tell: verbs of wanting, being able, having to and liking (querer, poder, deber, preferir) glue straight onto the infinitive — no a, de or que.
Quick check
Verb + infinitive
?How do you say "I begin to work" (from empezar a)?
Pattern 2 · takes "a"
Verb + a + infinitive
A big family of verbs needs a before the infinitive. Many involve starting, learning or movement toward an action:
empezar a — to begin to (empiezo a trabajar)
aprender a — to learn to (aprendo a nadar)
ir a — to be going to (voy a comer)
ayudar a — to help to (ayudo a cocinar)
volver a — to do again (vuelvo a intentar)
Memory hook: verbs of beginning and motion point toward the action — so they take a ("to / towards").
Pattern 2 · takes "de"
Verb + de + infinitive
Another family needs de. Several signal finishing or stopping:
acabar de — to have just (acabo de comer = I have just eaten)
dejar de — to stop (dejo de fumar)
tratar de — to try to (trato de ayudar)
terminar de — to finish (termino de leer)
Watch the meaning of acabar de: it does NOT mean "to finish". Acabo de comer = "I have just eaten" — the recent past.
Quick check
I have just eaten
?How do you say "I have just eaten"?
Pattern 2 · takes "que"
Verb + que + infinitive (obligation)
Two key expressions of obligation take que before the infinitive:
tener que — to have to (tengo que estudiar = I have to study)
hay que — one must / it is necessary to (hay que trabajar = one must work)
The difference:tener que is personal ("I have to"), while hay que is impersonal ("one must", no named subject).
Type it
Your turn — empezar a
1Write "I begin to work" (from empezar a).
Hint: empezar stem-changes (e→ie) → empiezo, then a + trabajar.
Sort it
Fill the preposition
al + infinitive
"On / upon doing"
Spanish expresses "on doing" or "upon doing" with al + infinitive — a neat, high-frequency construction:
Al llegar, me senté. — On arriving, I sat down.
Al ver la carta, sonrió. — On seeing the letter, she smiled.
Al salir de casa, empezó a llover. — On leaving home, it began to rain.
English trap: English uses "-ing" here ("on arriving"), but Spanish uses the infinitive — al llegar, never al llegando.
Type it
Your turn — acabar de
2Write "I have just arrived" (from acabar de).
Hint: acabo + de + llegar = "I have just arrived".
The gerund · formation
The gerundio (-ando / -iendo)
Form the gerund by dropping the ending and adding -ando (for -ar verbs) or -iendo (for -er/-ir verbs):
hablar → habl-
hablando
comer → com-
comiendo
vivir → viv-
viviendo
Two uses: (1) with estar for the continuous — estoy hablando = "I am speaking"; (2) for "by / while doing" — aprendo escuchando música = "I learn by listening to music".
Quick check
al + infinitive
?How do you say "on arriving"?
Type it
Your turn — form the gerund
3Write the gerund of hablar (to speak).
Hint: -ar verb → drop -ar, add -ando.
Sort it
"a" or "de" before the infinitive?
Sort each verb by the preposition it needs before an infinitive.
Takes 'a' before infinitive
Takes 'de' before infinitive
Infinitive as a noun
The infinitive is the noun form
Here is the rule that separates advanced Spanish from GCSE. Where English uses "-ing" as a noun or subject, Spanish uses the infinitive:
Ver es creer. — Seeing is believing. (both are subjects → infinitives)
Fumar es malo. — Smoking is bad.
After a preposition, always the infinitive: antes de salir (before leaving), después de comer (after eating).
Never use the gerund as a subject: Ver es creer, never Viendo es creyendo.
Quick check
The gerund of manner
?How do you say "I learn by listening" (to music)?
Game · Match
Match the expression to its meaning
Tap an expression on the left, then its meaning on the right.
EXPRESSION
al + inf
acabar de
tener que
hay que
dejar de
volver a
MEANING
one must
on doing
to do again
to have just
to stop
to have to
Type it
Your turn — al + infinitive
4Write "on arriving" (use al + infinitive of llegar).
Hint: al + the infinitive (not the gerund).
Infinitive vs gerund
The English-speaker's decision
English uses "-ing" for almost everything, so you must decide each time which Spanish form fits:
After a preposition → infinitive: después de comer (after eating).
As a subject / noun → infinitive: Nadar es sano (Swimming is healthy).
"By / while doing" → gerund: Aprendo practicando (I learn by practising).
With estar (continuous) → gerund: Estoy estudiando (I am studying).
Exam gold: using al + infinitive and acabar de + infinitive in your writing shows immediate IB-level range.
Quick check
Seeing is believing
?How does Spanish say "Seeing is believing"?
Type it
Your turn — tener que
5Write "I have to study" (from tener que).
Hint: yo form of tener is tengo, then que + estudiar.