A row of bikers wearing red and black.
Bikers in a gang are seen riding down the street.
A row of bikers are not necessarily in a gang. Bikers can also be stationary or off the road, not always riding down the street.
exists e1 s1 s2 x1 x2 x3.(a_topic(x1) & of(x1,x2) & for(e1,s2) & Theme(s2,x3) & a_black(s2) & for(e1,s1) & Theme(s1,x3) & a_red(s1) & Actor(e1,x3) & v_wear(e1) & (x2 = x3) & n_biker(x2) & n_row(x1))
exists e1 p1 x1 x2 x3.(n_street(x3) & exists e2 s1.(a_down(s1) & Manner(e2,s1) & Theme(e2,x3) & Actor(e2,x1) & v_ride(e2)) & Recipient(e1,p1) & Topic(e1,x1) & v_see(e1) & in(x1,x2) & n_gang(x2) & n_biker(x1))