a dog runs across the grass.
A dog runs in the field.
A field would have grass and a dog is running in both.
exists e1 x1 x2.(n_grass(x2) & across(e1,x2) & Actor(e1,x1) & v_run(e1) & n_dog(x1))
exists e1 x1 x2.(n_field(x2) & in(e1,x2) & Actor(e1,x1) & v_run(e1) & n_dog(x1))