a black car stopped in the road.
A black carstopped by police.
It is not apparent police stopped it.
exists e1 s1 x1 x2.(n_road(x2) & in(e1,x2) & Actor(e1,x1) & v_stop(e1) & n_car(x1) & a_black(s1) & Theme(s1,x1))
exists s1 x1 x2.(a_topic(x1) & by(x1,x2) & n_police(x2) & n_carstopp(x1) & a_black(s1) & Theme(s1,x1))