Estábamos sirviendo would be the answer for the nosotros form in the imperfect progressive. For future reference, you should check out the Spanish Dict online, it has all of the verbs in every form and tense :)
Classify the following verbs in time, person and number:- put - off- arrival
Answer:
pues no se wey pueste chigas vuscasdo tespuesta estudia wey para que lo sepas
