sentences:  Academy, with particularly high marks in airborne jump school and underwater maneuvers.When first introduced to S.H.I.E.L.D.Executive Director Nick Fury, the new agent's eager-beaver attitude meets initially with mock (and occasionally real) frustration from Fury and second-in-command Dum Dum Dugan, but Sitwell soon proves himself and earns his fellow agents' respect — albeit tinged with occasional humor aimed at his youthfulness and idealistic naïveté.