Three San Francisco Police Department cars were waiting in line at the corner of the street.
Some police cars are waiting to do something.
You can not infer there are police.
exists e1 x1 x2 x3 x4 x5 x6 x7 x8.(n_street(x8) & n_corner(x7) & at(e1,x7) & of(x7,x8) & in(e1,x6) & n_line(x6) & Actor(e1,x1) & v_wait(e1) & n_car(x1) & (x1 = x5) & ne_nam_department(x5) & (x1 = x4) & ne_nam_police(x4) & (x1 = x3) & ne_geo_francisco(x3) & (x1 = x2) & ne_geo_san(x2) & card_eq_3(x1))
exists e1 p1 x1 x2.(Topic(e1,p1) & Actor(e1,x1) & v_wait(e1) & exists e2 x3.(Theme(e2,x3) & Actor(e2,x1) & v_do(e2) & n_thing(x3)) & n_car(x1) & of(x1,x2) & n_police(x2))