A white dog running on sand.
A dog runs on top of the sand.
on sand refers to top of the sand.
exists e1 s1 x1 x2 x3.(a_topic(x1) & on(e1,x3) & n_sand(x3) & Actor(e1,x2) & v_run(e1) & (x1 = x2) & n_dog(x1) & a_white(s1) & Theme(s1,x1))
exists e1 x1 x2 x3.(n_sand(x3) & on(e1,x2) & of(x2,x3) & n_top(x2) & Actor(e1,x1) & v_run(e1) & n_dog(x1))