A black dog wearing a harness is pulling a sled.
A black dog was dragging a sled as he wore the harness.
Pulling and dragging are both forms of moving an object, so the dog with a harness is moving a sled.
exists e2 e1 s1 x1 x2 x3 x4.(Theme(e2,x4) & Actor(e2,x1) & v_pull(e2) & n_sled(x4) & Theme(e1,x3) & Actor(e1,x2) & v_wear(e1) & n_harness(x3) & (x1 = x2) & n_dog(x1) & a_black(s1) & Theme(s1,x1))
exists e1 p1 s1 x1 x2 x3.(n_harness(x3) & exists e2.(Theme(e2,x3) & Actor(e2,x1) & v_wear(e2)) & n_male(x1) & as(e1,p1) & Theme(e1,x2) & Actor(e1,x1) & v_drag(e1) & n_sled(x2) & n_dog(x1) & a_black(s1) & Theme(s1,x1))