Does dimostrato agree with the object rather than the subject of the sentence, otherwise 'He has shown her - should be acceptable?
Yes, when using a clitic with the auxiliary avere the past participle can agree with the object, and it's mandatory with l' to differentiate between "lo" and "la".
But in this case it is" Lui l'ha dimostrata", I think
It depends on what «l'» stands for. If «l'» stands for «la presentazione», then it would be «Lui l'ha dimostrata.». If «l'» stands for «il rapporto», then it would be «Lui l'ha dimostrato.».
Shouldn't be OK "He has proven it"? Thanks in advance.
See my comment here: https://www.duolingo.com/comment/1019808 :)
this comment, although correct, does not apply to this particular sentence. 'prove' is definitely a correct answer here.
I was wondering the same thing. Does anybody have an answer / explanation?
Was marked wrong for using prove. But I think that it should be correct.
The system never accepts my spoken items so I recorded it and played it back. It still did not accept!
So how would you say 'Show yourself'?
Perhaps «Mostrati.». I think of «mostrare» as "to show" and «dimostrare» as "to demonstrate."
What about translating "dimostrato" with "proved". (He proved it.)?
Duo would not accept: He "proved" it. Dimostrare can also mean: prove, demonstrate, or show