"Tomorrow he will have written the letter."
Translation:Morgaŭ li estos skribinta la leteron.
I'm guessing that the rule about not using the accusative -n with Esti does not apply when esti is an auxiliary verb.
Am I correct in guessing that I can in principle write "estos skribinta" as "skribintos"? (as adjectives can do) Such plasticity would really blow my mind!