Spanish language Q&A Forum

In the example, "We saw a very interesting film at the cinema", why isn't el Pretérito Indefinido used, i.e. "Vimos" instead of "Hemos visto"?   I would think that hemos visto would be used in the following case, "We have seen a very interesting film at the cinema". I can't tell which tense to use.

Why is it rey del vino instead of rey de vino?

________ del colegio tendrás que hacer tus deberes.

When you get back from school you will have to do your homework.

Cuando volverás

Cuando hayas vuelto

Cuando volverías

Cuando volviste

The right answer is "hayas vuelto" , but I don't understand why "volverás" is wrong. 

My husband is from Costa Rica 

Surely " foggy" is an adjective . The noun is " fog" !  So why not use "está "  for " it is foggy "  _

One of my lesson tests on Poder in the subjunctive asks, 

No dudo que vosotras ________ correr tan rápido como ellos.I have no doubt you can run as fast as them.(HINT: Conjugate "poder" in El Presente Subjuntivo.)

But why would you use the subjunctive here? No  dudo, I have no doubt, is an expression of certainty. Everywhere else that I have learned (my college course, spanishdict translation and google translation all use the indicative for No hay duda que..., and I figure this ought to be similar.

The example has hay with foggy but esta with sunny. I don’t understand 

Just want to mention that they often use this "Impersonal Third Person Plural" construction for newspaper headlines here in latin America.

Siempre he oído Día de LOS Muertos.