I have successfully completed all grammar topics in Spanish, however one topic is still puzzling for me: the infinitive.

I often find myself trying to sell, "It is difficult to explain" in Spanish. But I have no idea how?! Is it, "Es difícil explicar."? That sounds wrong, but I just don't know. Also, I see the construction " para + infinitive", but can't kind the correct definition of if or when to use it. What are the many ways to use the infinitive of a verb?

I will provide some examples:

  1. Adjective + verb

  2. Para + verb

  3. De + verb

  4. Por + verb

  5. Infinitive alone

If you could write about any other places that one might use the infinitive, that would be great!

  • When the infinitive is written to express a purpose, to = para: I came here to work = vine aquí para trabajar; es difícil explicar is idiomatic, but it often needs an object, es difícil explicar lo siguiente but when we have already spoken of something, it's often written along with de: es difícil de explicar.
    – Schwale
    Jan 20, 2016 at 3:45
  • The use of "Para" + infinitive depends on the verb. "Para trabajar", for example, should be replaced with "A trabajar". Sounds better. On the other hand, "Para ver" is correct and can't be replaced with "A ver" in the same sentence. "Voy a ver" is correct while "Voy para ver" is not. Check this answer to have a better idea. Jan 20, 2016 at 4:50
  • helper verb + [a/que] + infinitive: with a determiner in between, these usually are used for progressive tenses. "Voy a comer", or "Tengo que irme", "Me hubiera gustado estudiar, [pero el ruido era demasiado]" I believe DETERMINER + INFINITIVE is used for verbs that don't tend to allow the subject as also the direct object. Jan 20, 2016 at 14:14
  • This post explains the difference between por + verb and para + verb. This one explains the difference between verbs preceded by "a" and bare infinitives. If you ask a question already answered, explain why the available answer does not fully adress your concerns. Otherwise, it might get closed.
    – Yay
    Jan 20, 2016 at 14:42

1 Answer 1


No wonder you find this puzzling: from the grammar point of view, this specific construction is quite difficult. I've found a 15-page study of this construction that explains it pretty well, though.

In short: a construction such as It is difficult to explain can also be written in English as Explaining it is difficult. I'll use a different subject to make this clearer:

History is difficult to explain => Explaining History is difficult

The construction pattern is noun + to be + adjective + to + infinitive, where the adjective qualifies the noun and the infinitive acts as modifier of the adjective, but the noun is also the object of the verb (what is difficult to explain? History).

In these cases, the appropriate preposition to use in Spanish is de:

Es difícil de explicar

Once again, the example with a different subject and both forms:

Tu comportamiento es difícil de explicar => Es difícil explicar tu comportamiento (or: explicar tu comportamiento es difícil)

This construction works with many different adjectives:

Tu comportamiento es difícil de explicar

La lección es fácil de entender

La película es imposible de olvidar

El examen está pendiente de corregir

Una camisa cómoda de llevar

As you can see in the last examples, the verb ser can be replaced by others, such as estar, or even omitted altogether; but the construction is still the same. In all those cases, the subject of the sentence (or proposition) also works as object of the infinitive that modifies the article.


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