Click here for a review of common forms with irregular roots in the preterit. The imperfect subjunctive will therefore be “durmiera”. For example, “dormir” has a stem change in the 3rd person forms of the preterite: durmió, durmieron. If a verb has an irregular stem in the 3rd person plural (ellos) form in the preterit, it is maintained in the imperfect of the subjunctive.
Because the subjunctive is used in most of the same contexts in the past, it is a good idea to review this information before starting this section. In Unidad 3 we learned about when the subjuntive mood is used in present and future contexts. In this section we will learn that the subjunctive mood is also employed when referring to past actions, events and states. Usando el subjuntivo en el pasado - El imperfecto del subjuntivo Cláusulas con "si" en situaciones hipotéticas.