To form the imperfect continuous you use imperfect tense of the verb estar + the present participle of the verb that tells what you were doing.
Example: Los niños estaban jugando fuera y los vecinos estaban hablando en voz baja.
Translation: The children were playing outside and the neighbours were speaking quietly.Spymore
you use estar + present participle to form the imperfect continuous form.
mediacorp? that is my guess