Tipo III - Third Conditional
Il periodo ipotetico di tipo III (Third Conditional) serve ad indicare eventi impossibili riferiti a situazioni passate.
Forma
secondaria (if clause) principale (main clause) =
if + trapassato (past perfect) condizionale passato (past conditional)
If I had had time, I would have visited India.
Come per il tipo 2 would può essere sostituito da un modale e possono essere usate le forme progressive nella frase principale e secondaria.
They would have spent a fortnight with us If they had had time.
They could have spent a fortnight with us If they had had time.
They might have spent a fortnight with us If they had had time.
Mary would have been cooking if we hadn’t invited her to dinner.
If he had been catching the train, he would have been here tonight.
E’ possibile usare nella preposizione principale il condizionale presente (would + forma base) , come nel periodo ipotetico di II tipo, invece del condizionale passato (would have + participio passato), quando il risultato dell’azione viene riferito al presente e non al passato
If we had taken a direct flight, we would already be in New York now.