Dog digs in sand
A dog is at a beach
Digs in sand does not necessarily mean at a beach.
exists e1 x1 x2.(ne_nam_dog(x1) & in(e1,x2) & n_sand(x2) & Actor(e1,x1) & v_dig(e1))
exists p1 x1.(exists x2.(at(x1,x2) & n_beach(x2)) & n_dog(x1))