I put "he wants to demonstrate that he can do it" and was marked wrong - am I wrong - the answer suggested "we can do it" as an alternative - how does it get "we"??
I made the same mistake. I suppose that we can read the sentence that way : "Lui vuole dimostrare che esso si può fare" which would explain the answer : "that it can be done". I assume that if it can be done, then we can do it. Tricky one :)