Workers are sorting items in a truck.
People are in the truck.
Workers are also people and they being sorting items in truck means they are in truck.
exists e1 x1 x2 x3.(in(e1,x3) & n_truck(x3) & Theme(e1,x2) & Actor(e1,x1) & v_sort(e1) & n_item(x2) & n_worker(x1))
exists p1 x1 x2.(n_truck(x2) & in(x1,x2) & n_people(x1))