Obligation and aspect periphrases

A verbal periphrasis is a two-part verb construction made up of a conjugated auxiliary plus an infinitive (sometimes linked by a preposition), which together express a single verbal idea. The periphrases covered here fall into two groups: modal periphrases, which express obligation or necessity (tener que, hay que), and aspectual periphrases, which locate an action in relation to its start, repetition, or recent completion (empezar a, volver a, acabar de, soler). Object pronouns (clitics) can attach to the infinitive or, with most periphrases, move to precede the conjugated auxiliary — a process called clitic shift.

• tener que + infinitive — personal obligation. The subject is responsible for doing something. Equivalent to English «have to» or «must».

• hay que + infinitive — impersonal necessity. No specific subject; it applies to people in general. Equivalent to «one must» or «you have to» (in a general sense). Hay never changes form.

• acabar de + infinitive — recent completion. The action has just finished moments ago. Equivalent to «to have just done».

• empezar a + infinitive — beginning of an action. Equivalent to «to start doing» or «to begin to do».

• volver a + infinitive — repetition of an action. Equivalent to «to do again».

• soler + infinitive — habitual or customary action. Equivalent to «to usually do» or «to tend to do». Used in the present and imperfect only.

All six periphrases follow the same skeleton: conjugated auxiliary (+ preposition) + infinitive. The table below shows the present-tense forms of each auxiliary. Hay que has only one form for all persons.

Clitic placement. With tener que, acabar de, empezar a, volver a, and soler, the object clitic may either attach to the infinitive or shift to precede the conjugated verb — both positions are correct.

• Shifting the clitic before hay que. Because hay que is impersonal and has no personal subject, there is no conjugated verb that «belongs» to a subject, so the clitic cannot shift forward. *Lo hay que hacer is ungrammatical. The only correct form is hay que hacerlo.

• Confusing the periphrastic and literal meanings of volver a and acabar de. Volver alone means «to return»; volver a + infinitive means «to do again». Similarly, acabar alone means «to finish»; acabar de + infinitive means «to have just done». Compare: Vuelvo a casa (I return home) vs. Vuelvo a llamar (I call again); Acabo el libro (I finish the book) vs. Acabo de leerlo (I have just read it).

• Using soler outside the present or imperfect. Soler exists only in the present and imperfect tenses in standard Spanish. Avoid forms like *solí or *soleré. When you need to express habitual action in other tenses, use normalmente or generalmente with the appropriate tense instead.