Future indicative is formed into the periphrastic conjugation in "-urus sim " ( present periphrastic subjunctive, used as the future subjunctive ), or in "-urus essem " ( imperfect periphrastic subjunctive ).
2.
Nevertheless, the use of present subjunctive after a primary tense and imperfect subjunctive after a secondary tense is also strongly attested, especially when the future reference is obvious from contextual parameters and in the case of a passive verb ( passives luck the periphrastic conjugation-urus sim etc . ).