Two boys play in the sand
 Two boys play in the sand box.
The boys are playing in a sand box, therefore playing with sand.
exists e1 x1 x2.(n_sand(x2) & in(e1,x2) & Actor(e1,x1) & v_play(e1) & n_boy(x1) & card_eq_2(x1))
exists e1 x1 x2 x3.(n_box(x2) & of(x2,x3) & n_sand(x3) & in(e1,x2) & Actor(e1,x1) & v_play(e1) & n_boy(x1) & card_eq_2(x1))