Four dirt bike riders are riding on a dirt road.
The people are riding down a dusty road.
Just because it is a dirt road doesn't mean it's dusty.
exists e1 x1 x2 x3 x4 x5.(on(e1,x4) & n_road(x4) & of(x4,x5) & n_dirt(x5) & Actor(e1,x1) & v_ride(e1) & n_rider(x1) & of(x1,x3) & n_bike(x3) & of(x1,x2) & n_dirt(x2) & card_eq_4(x1))
exists e1 s1 s2 x1 x2.(n_people(x1) & a_down(s2) & Manner(e1,s2) & Theme(e1,x2) & Actor(e1,x1) & v_ride(e1) & n_road(x2) & a_dusty(s1) & Theme(s1,x2))