Spanish language Q&A Forum

When is de used after faltar?

I've read it's mostly a formal construction?

"Yo visité unos cuarentas países cuando era joven" (taken from a test, correct answer), pero "unos ochenta minutos". 

I would have expected that "unos cuarenta países" is correct. Why isn't it?

In the exercise the phrase 'Haciendo la compra a mis mayores' is used. I would have expected 'para mis mayores'. Is the use of 'a' instead a common Spanish usage?

You should just ask a straight up question and not try to fool us. 

Hola! Necesito un poco de ayuda con una frase. No entiendo porque en esta frases ''A continuación, agregue tomates triturados, alcaparras, aceitunas, una hoja de laurel y el bacalao desmenuzado a la sartén'' decimos ''a la sartén'' en lugar de ''en la sartén''. Gracias! :-)

In a previous question, mover was used in a present tense (Ella mueve...). However, in this quiz, mover was used in a reflexive tense (El perro se mueve). How do we know when to use or not use the reflexive tense? 

I notice that you consider as correct all answers that are theoretically correct from a grammatical perspective, even if they are not idiomatic and it is highly unlikely that a Spanish speaker would use the expression. Example: “No deberías nunca salir con ella.” Or am I missing something?