A dog walks along a beach.
A dog is walking.
Walks is the same as is walking.
exists e1 x1 x2.(along(e1,x2) & n_beach(x2) & Actor(e1,x1) & v_walk(e1) & n_dog(x1))
exists e1 x1.(Actor(e1,x1) & v_walk(e1) & n_dog(x1))