Spanish language Q&A Forum

I'm confused about the use of imperfect tense (éramos) in this sentence below, rather than preterite (fuimos). I understand the knocking on the door as a specific, completed action that took place at a specific point in time, which I understand as characteristic of preterite (We knocked on the door/It was us who knocked on the door.). I understand the use of imperfect to discuss ongoing, continuous actions, so I'm confused in this example, because a knock is not an ongoing action that continues over time. I'm sure I'm missing something in my understanding; I'd appreciate some advice! Gracias!

Éramos nosotros los que llamamos a la puerta.

This is the best audio so far! Crisp and clear and nicely spaced. Thank you, Silvia!

In the quiz to find out which level you are, I was marked wrong for putting "hay" instead of "tiene" in the question about the city having a pool. Why is it giving me two different answers now? 

In the lesson it says convertirse en and hacerse can both be used to talk about a career change with the former indicating a more drastic change. However in the quiz both answers are listed (for a sentence about a career change) but only hacerse is marked as being correct. 

this comment has been deleted just in time before making a fool of myself.

What about the (even in English) problematic decade of 2000-2009? 

or 2010-2019 ?

In the statement:  "Nosotros solemos comer en casa de mis padres los domingos."

Why don't we use "la casa de mis padres"?

Thanks.

Hace mucho frío en Canadá. 

I don't understand why " mucho" is used here.