Teenagers are looking out the window of a bus.
Teenagers are at a field.
One cannot be looking out the window and at a field at the same time.
exists e1 x1 x2 x3.(n_window(x2) & out(e1,x2) & of(x2,x3) & n_bus(x3) & Actor(e1,x1) & v_look(e1) & n_teenager(x1))
exists p1 x1.(exists x2.(at(x1,x2) & n_field(x2)) & n_teenager(x1))