The child is walking through straw.
The child is on a farm.
The child might not be on a farm.
exists e1 x1 x2.(n_child(x1) & through(e1,x2) & n_straw(x2) & Actor(e1,x1) & v_walk(e1))
exists p1 x1.(n_child(x1) & exists x2.(on(x1,x2) & n_farm(x2)))