A dog plays in water.
The dog is on the grass.
Water and grass are different.
exists e1 x1 x2.(in(e1,x2) & n_water(x2) & Actor(e1,x1) & v_play(e1) & n_dog(x1))
exists p1 x1 x2.(n_grass(x2) & n_dog(x1) & on(x1,x2))