A zebra is nibbling on some grass.
There is an animal eating.
zebra is eating grass
exists e1 x1 x2.(on(e1,x2) & n_grass(x2) & Actor(e1,x1) & v_nibble(e1) & n_zebra(x1))
exists p1 x1 x2 x3.((x1 = x2) & n_eating(x2) & of(x2,x3) & n_animal(x3))