Once escuelas contra el calor: los refugios climáticos de Barcelona

passive se in the past

se transformaron once escuelas

eleven schools were transformed

Se transformaron is a passive se construction. The plural verb agrees with once escuelas.

Useful for formal reports that focus on the result rather than the actor.

antes de que plus subjunctive

Antes de que empezaran las obras

before the works began

Antes de que introduces a different subject and is followed here by the imperfect subjunctive empezaran.

Helps connect two past events with different subjects.

sin plus infinitive

sin dejar de usar el patio

without ceasing to use the playground

Sin followed by an infinitive expresses an action that does not occur while another action does.

Useful for stating that one goal does not cancel another.

siempre que as a condition

siempre que no necesitaran atención médica

provided that they did not need medical care

Siempre que introduces a condition here, so it is followed by the imperfect subjunctive necesitaran.

Useful for adding a precise limitation to a recommendation.

podía plus infinitive

podía convertirse en un recurso

could become a resource

Podía plus the infinitive convertirse expresses a possibility in a past context.

Helps discuss the potential of an earlier plan or situation.