A group of bike riders are riding on the street.
The bikers are riding fast.
Not all bike riders ride fast.
exists e1 x1 x2 x3 x4.(n_street(x4) & on(e1,x4) & Actor(e1,x1) & v_ride(e1) & of(x1,x2) & n_rider(x2) & of(x2,x3) & n_bike(x3) & n_group(x1))
exists e1 s1 x1.(n_biker(x1) & a_fast(s1) & Manner(e1,s1) & Actor(e1,x1) & v_ride(e1))