A gang of bikers sit in traffic.
some guys are doing something
You don't have to be in traffic to be doing something.
exists e1 x1 x2 x3.(in(e1,x3) & n_traffic(x3) & Actor(e1,x1) & v_sit(e1) & of(x1,x2) & n_biker(x2) & n_gang(x1))
exists e1 x1 x2.(Theme(e1,x2) & Actor(e1,x1) & v_do(e1) & n_thing(x2) & n_guy(x1))