"What do you demonstrate" was a right response, although I don't understand why.
It would be if you address somebody you don't know with "lei" or "lui" to be polite, and then it would conjugate at the third person singular.
Yes. Then the subject of the sentence is third person singular formal (Lui / Lei)
Here's an excellent reference site for all the pronouns (really helpful when you need the indirect object pronouns for verbs like piacere and mancare ... those are covered farther down on the site)
For some reason, when you hover the mouse of the verb, it says "you" rather than "he/she." This is a mistake.
I was dinged for using the formal "you" even though it was first in the hints
I wrote "what do you show" and it didn't get accepted. "What does it show?" - that's the correct solution by duolingo, yet the hover-on tip says that "dimostra" means "YOU demonstrate"...
Why not "Cosa lo/la dimostra."
I saw the same thing with significa in "Cosa significa per noi?", which was translated as "What does it mean for us?"
Is there a grammar rule that I'm missing here about the verbs themselves,or the structure of cosa+verb, that would ultimately imply the "it" in the sentence so you won't need "lo/la"
Or is it just third person conjugation, meaning you could translate this as "What does he/she show" as well?
In "Cosa lo/la dimostra" lo/la is a direct object (him/her/it). Its usage here is wrong because "cosa" already represents the direct object. The subject (lui/lei) is optional in Italian, but not in English (he/she/it).
- (Lui/lei) cosa lo/la dimostra (a qualcuno)? = What does he/she show him/her/it (to someone) ?!?!?
Without "cosa" the sentence is grammatically correct:
- (Lui/lei) lo/la dimostra (a qualcuno)? = Does he/she show him/her/it (to someone)?
Alternatively an indirect object can be used:
- (Lui/lei) cosa gli/le dimostra? = What does he/she show to him/her/it?
The actual sentence can be rephrased to be more grammatically obvious:
- Cosa dimostra? = What does it show? (direct-object + subject + verb)
- Dimostra cosa? = It shows what? (subject + verb + direct-object)
Synonym of "demonstrate" is "show". Therefore if I answer "show" this is not an error. Please correct
"What does that show?" is wrong, though in other sentences "that" is accepted despite not being formulated like ... that.
No, that would be ungrammatical. You would say "cosa dimostra" or possibly "cosa sta dimonstrando".
"what is it demonstrating" is "cosa sta dimostrando". In my opinion, it could be a valid translation for "Cosa dimostra", but maybe Duolingo likes a more literal translation.