Use of imperfect subjunctive

Question

HolaWhy is the imperfect subjunctive used, as it is not a repeated or continued action?  Many thanks

Answer

Hola Janet,
The imperfect subjunctive doesn't have the same use as the Imperfect indicative. The imperfect indicative (tenía, había, trabajaba...) indicate actions that are repeated in the past or continuous actions in the past as you said; but the imperfect subjunctive in this sentence from the lesson:

No creo que Susana viniera hoy. 
(I don't think Susana came today.)

doesn't mean that she used to come. It simply means she didn't come (or you think she didn't)
Saludos
Inma