You can, and it may be translated as "Can you (Ustedes) show that?" The 'ellas' clarifies the subject.
I read this as 'can they show that to them?' Wrong. Perhaps that would be 'Pueden las demostrar a ellas eso?
that is close but "to them" would be the indirect object "LES". Not the direct object LAS.
you can say "Can the girls demonstrate that?" why is that not an option?
ellas = they (all female, women or girls) las niñas = the girls and only the girls
Bridgette, I agree with you to an extent. You cannot use the word "girls" because you don't know the ages but you should be able to use the words "the females". English does not have a masculine and feminine "they" but Spanish does. So the translation "Can they show that?" does not completely translate all of the information to English. The Spanish speaker knows that the "they" means more then one females but the English speaker would have no idea other than there are more than one of them.
Imagine you are a student in a cooking class. In front of you there are two tables. The table on the left has 2 ladies making a caesar salad. The table on the right has 2 guys making the same. The instructor is at the point where they are adding the coddled egg and is explaining how to coddle an egg. You raise your hand and ask "Pueden ellas demostrar eso?" and the table on the left start to demonstrate. But if you raise your hand and ask "Can they show that?" both tables will start to demonstrate.
So even if Duolingo accepts the incomplete translation of "Can they show that?", they should also accept the complete translation of "Can the females show that?". Reported 12-19-17
Not a fan of that. :´)
Granted, in this sentence someone's doing the showing/demonstrating/proving, so you'd expect the subjects to be humans, mostly, which are female about half the time, but ellas doesn't always refer to humans. A group of tables can be ellas just as well, but I don't think you'd describe tables as "female" in English.
My dictionary lists "demonstrate" as one of the translations of "demonstrar". But Duo does not accept it. Will report.
The English seems more like a question of permission rather than ability. Is this the same in Spanish?
To me it sounds more like a request - I politely want them to do it. The Spanish sentence can represent all these nuances.
"To prove" tends to be used more frequently as a verb but "to proof" can still be used as a transitive and intransitive verb :)