A boy plays in the sand.
A child is playing with sand.
The child playing in the sand is a boy.
exists e1 x1 x2.(n_sand(x2) & in(e1,x2) & Actor(e1,x1) & v_play(e1) & n_boy(x1))
exists e1 x1 x2.(with(e1,x2) & n_sand(x2) & Actor(e1,x1) & v_play(e1) & n_child(x1))