The imperfect, or past, subjunctive is the simple past subjunctive in Spanish. It is subject to conditions similar to those governing the present subjunctive, i.e. it normally occurs in complex sentences with changes of subject and with appropriate verbs or conditions expressed or implied by the main verb in the independent clause.
If the verb in the main clause is in one of the past tenses or if it refers to the past, and if the subjunctive is required in the subordinate clause, the main verb will be expressed in the imperfect subjunctive.
The endings of the imperfect subjunctive are the same for
-ar, -er, and -ir verbs. One simply adds the
appropriate ending to the preterite
tense verb stem to arrive at the proper form. There are no
irregular endings, but there are numerous irregular stems. The stem
to which the forms are added is the third person plural of the
preterite tense, less the final -ron. To this stem
add:
Plural
A second set of less commonly used endings is also available.
They are:
Plural
Some examples of the imperfect subjunctive follow, as applied to both regular and irregular verbs:
All of the conditions that require the use of the present subjunctive (i.e. sentence structure,
change of subject, and appropriate verb/conditions) apply to the
use of the imperfect subjunctive. The primary difference in its use
is governed by the logic of the sentence, also known as the
"sequence of
tenses." If all conditions for the use of the subjunctive are met
in a sentence and the tense of the verb in the main clause is in
the past (preterite, imperfect, pluperfect, or conditional), the imperfect subjunctive will
follow.
The imperfect subjunctive can also follow a main clause
containing a verb in the present if the reference is clearly to the
past:
1. Clauses introduced by the word si (if) require the
imperfect subjunctive or pluperfect subjunctive if the main
clause contains the conditional or
conditional perfect.
In the following sentence structures the usual requirements for the
use of the subjunctive do not apply.
2. The imperfect
subjunctive always follows como si (as if).
3. The imperfect subjunctive is often used to soften a request
or an assertion.
"If" constructions
Imperfect indicative
Preterite
Present subjunctive
Verbs