Uses of the Infinitive

infinitive after conjugated verb

used after verbs (like deber, decidir, desear, necesitar, pensar, poder, preferir, querer, saber) when there is no change in subject

infinitive after verb of perception

used after escuchar, mirar, oír, sentir, ver with a direct object pronoun

infinitive after verb of influence

used after dejar, hacer, mandar, permitir, prohibir instead of a subordinate clause

infinitive after impersonal expressions

es bueno, es importante, hay que, tener que, es fácil to express general statements

infinitive instead of gerunds

spanish does not use -ing as nouns

infinitive in signs and instructions

used for commands and warnings

infinitive after prepositions

after para, sin, antes de, después de to complete an idea

to have just done something

acabar de + infinitive

to learn to do something

aprender a + infinitive

to teach to do something

enseñar a + infinitive

to agree to do something

quedar en + infinitive

to take time to do something

tardar en + infinitive

to try to do something

tratar de + infinitive

obligation to do something

deber + infinitive

probability to do something

deber + de + infinitive