"Stay with him until he does the work."
Translation:הישארי איתו עד שהוא יעשה את העבודה.
No. The pronouns אני אתה את אנחנו אתם אתן (first and second person) are not needed in past and future tense, as far as I know (but duolingo often insist on using/requiring אני in first person future tense). The third person pronouns הוא היא הם הן are usually required in all tenses.