Spanish language Q&A Forum

In the quiz, I got the sentence

Antes de que tú digas nada, .... ( before you say anything )

Why is 'nada' here ? Can it be 'algo' ?

Another example from the other lesson is, though I don't remember the exact phase but it's like

No creo que hayan llegado todavía.

The original phase to be denied should be 'han llegado ya'. Again, why it changed to 'todavía' ?

I agree that whole expression has something negative, which hasn't happened yet. But I'm confused, because the phase in 'que' is totally affirmative.

So the expression in 'que' isn't independent from its use ? And how ?

what does afueras de la ciudad mean? 

 Al haberse portado tan mal, lo expulsaron del colegio.

the pronoun se came right after haber not after portado nor in front of haber.

This is different from any other rules I knew, like:

Me lo dijo. Me lo ha dicho. Dímelo ! Quiero dárselos.

So which rule applies to this ? 

FYI: this sentence in English is incorrect.

I bought her some books about Mexico in case they were useful for his trip to Acapulco.

"in case they would be useful"

Finding this lesson on Kwiziq has proved a real revelation for me!  I've been learning Spanish for the last 3-4 years through online courses geared toward Latin American Spanish and wasn't aware of this difference. I've always been aware of some regional vocabulary differences but, since I've geared my learning toward Peninsular Spanish (which I need), I'm now finding quite a few grammatical differences too. I had seen the perfect used in this way in El País articles and books etc but I'd not been able to find any resource that actually explained it... until now! 

Could you answer how specific times might influence choose of tense? 

I spoke to him at 3am this morning 

His flight left at 6pm today

These specific times seem to indicate start and finish times. Do they point toward preterite?

Puedo decir,  “para conocer a uno de mis actores preferidos”, también?

I think there is an error in this example translated sentence - pencil is mentioned 2 x.

Prefiero aquellos lápices de colores.

I prefer those pencil coloured pencils (over there).

I'm a bit confused by this example. Why is it "al que"? Could it be "al cual"? Thanks for your help!

MOTHER: Of course, the guy who you met at the Spanish course at University,