Two little boys play football on green grass.
The boys have grass stains on their clothes.
The grass stains may be a result of playing football. not all grass stains result from playing football.
exists e1 s1 s2 x1 x2 x3.(on(e1,x3) & n_grass(x3) & a_green(s2) & Theme(s2,x3) & Theme(e1,x2) & Actor(e1,x1) & v_play(e1) & n_football(x2) & n_boy(x1) & a_little(s1) & Theme(s1,x1) & card_eq_2(x1))
exists e1 x1 x2 x3 x4.(n_clothes(x4) & of(x4,x1) & n_thing(x1) & n_boy(x1) & on(e1,x4) & Theme(e1,x2) & Actor(e1,x1) & v_have(e1) & n_stain(x2) & of(x2,x3) & n_grass(x3))