Subjunctive — in Adverbial Clauses

Subjunctive — in Adverbial Clauses

The subjunctive is also used in Spanish in adverbial clauses introduced by certain conjunctions expressing future condition or event, purpose or result, concession or supposition. The principal conjunctions used in this way are:

a) cuando, antes de que, hasta que, tan pronto como, mientras (expressions of time)

b) para que, a fin de que, de manera que, sin que (expressions of purpose)

c) aunque, menos que, con tal de que, suponiendo que (expressions of concession)

The reason for using the subjunctive in Spanish in such sentences is that, after the various conjunctions mentioned, a future or hypothetical situation, which has not yet become a factual one, is indicated; therefore, logically, a subjunctive rather than an indicative form is called for. If, of course, a definite situation or accomplished fact is indicated, then, as in English, the indicative mood is used.

Yo le preguntaré cuando él venga.
I'll ask him when he comes.

Iremos tan pronto como llegue Juan.
We'll go as soon as Juan arrives.

Le doy este libro para que lo lea.
I give you this book so that you may read it.

BUT:

Felipe era muy joven cuando llegó a ser rey.
Felipe was very young when he became king.

Salimos anoche tan pronto como llegó Juan.
We went out as soon as Juan arrived.

Hablamos hasta que se fue.
We talked until he left. (Both definitely completed past actions; therefore no subjunctive.)