Spanish language Q&A Forum

This was the question in the test that led me to this lesson,  but the lesson doesn't address the issue of choosing the correct past tense.

Ustedes ________ separados el año pasado.You were separated last year.
The hint tells you to use the tense for estaban, but I don't understand why since this seems to be talking about a definitive time that something happened.  Either the action of separating happened last year or the circumstance of being separated happened last year. Can someone explain why we should choose estaban over estuvieron (ustedes) besides the fact that the "hint" tells us to?
Thanks in advance for  any help!

I am unsure why you choose imperfect for being able to see the view on that particular occasion. 

"Mi padre no es ________ maestro".

The question is "my father is not THEIR teacher" - so why is the answer "su", why not "sus" when it is their not his/her?

Is there a difference between using ´en´ and ´por´.

For example ´voy a hacerlo por/en la mañana´?

In Question 6 of the quiz, 'podamos' is used in the sentence. Shouldn't this be 'podemos' or is it used in the subjunctive tense?

Thank you.