Spanish language Q&A Forum

What is the difference between these 2? Both are expressing action in progress but I'd like to be more clear about when we would use each.

¿Qué es la diferencia entre las palabras rincón y esquina?

“Maria told us there was a meeting at 4”

hubo is incorrect here, but I thought with a set time it became ‘hubo’? What am I missing? 

I wrote "La familia está" since it seems to discuss a relationship. The correct answer is given as "La familia es". So, "es" seems to be a strong opinion. Couldn't both be correct?

Also, the issue with my answer doesn't really relate to plural versus singular ("es" vs "está"). 

Why is cambiar used with the preposition de and sometimes without? Is there any difference between the two ways of using cambiar?

In the sentence:Ellas a luz a unos gemelos preciosos. (They gave birth to beautiful twins),

1) does "ellas" indicate 'several women gave birth to several sets of twins'? 

2) If a married couple had A set of twins, would that be ' ellOs a luz a un gemelo precioso?, Or does 'a luz' literally only refer to the mother who gives birth?

Thanks

In the sentence: my girlfriend says that you will be worth it.  Why would you use valdrás, instead of valdrá la pena?  You are not valuing it, you are just worth it.