al + Infinitive

Upon Doing (Al)

Level 4

'Al + infinitive' means 'upon/when doing something'.

How It Works

The construction al + infinitive is a common and elegant way to express simultaneous or immediately consecutive actions. It's a more concise alternative to using a clause with 'cuando' (when).

Formation:
The structure is formed with al, a contraction of the preposition a and the definite article el. The infinitive retains verbal properties and can take objects and its own subject.

  • Al llegar = literally 'at the arriving' -> 'upon arriving'
  • Al ver = literally 'at the seeing' -> 'upon seeing'

Subject of the Infinitive:
Usually the subject of the infinitive is the same as the subject of the main verb.

  • Al llegar a casa, yo preparé la cena. (Upon arriving home, I prepared dinner.) The subject 'I' performs both actions.

The subject can also be different. A different explicit subject commonly follows the infinitive:

  • Al entrar el profesor, los alumnos se levantaron. (Upon the teacher entering, the students stood up.)
  • Al llegar la primavera, florecen las plantas. (When spring arrives, the plants bloom.)

For this temporal use, you can rephrase with cuando as an alternative:

  • Cuando llegué a casa, mi madre preparó la cena. (When I arrived home, my mother prepared dinner.)

The subject-after-infinitive order is widely used. Subject-before-infinitive forms such as 'al yo llegar' also occur, especially in Caribbean varieties, and should not be treated as universally ungrammatical.

'Al + infinitive' can also express a reason, depending on context: Al no tener dinero, no pude comprarlo. (Since I had no money, I couldn't buy it.)

Examples (5)

  1. Al entrar en la habitación, encendí la luz.

    Upon entering the room, I turned on the light.

    Word by Word: Upon to enter in the room, I turned on the light.

  2. Se puso nervioso al hablar en público.

    He got nervous when speaking in public.

    Word by Word: He became nervous upon to speak in public.

  3. Al terminar el trabajo, nos fuimos a celebrar.

    Upon finishing the work, we went to celebrate.

    Word by Word: Upon to finish the work, we went to celebrate.

  4. Descubrí el error al revisar los documentos.

    I discovered the error upon reviewing the documents.

    Word by Word: I discovered the error upon to review the documents.

  5. Al salir del cine, nos dimos cuenta de que llovía.

    Upon leaving the cinema, we realized it was raining.

    Word by Word: Upon to leave from the cinema, we realized that it was raining.

Common Mistakes

  • Using a conjugated verb directly after temporal 'al'.

    Al llegué a casa, mi madre preparó la cena.
    Al llegar yo a casa, mi madre preparó la cena.

    Use an infinitive after 'al': llegar. With conjugated llegué, use Cuando llegué a casa. This card does not reject the regional subject-before-infinitive order al yo llegar.

How It Connects

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al + InfinitiveLevel 4Upon Doing (Al)

Learn This First

To understand 'al + infinitive', you first need to recognize the contraction 'al' (a + el) and be familiar with the infinitive form of Spanish verbs, which serves as the verbal noun in this structure.

Words in This Pattern