A looker on catches a motocross bike on its side after a spill while another races by.
A motorcycle is laying on its side.
A motorcycle is a motocross bike.  If the bike took a spill, it would be laying on its side.
exists e1 s1 x1 x2 x3 x4 x5 x6 x7.(n_race(x6) & a_by(s1) & Manner(e1,s1) & while(e1,x7) & n_race(x7) & -(x7 = x6) & rel(e1,x3) & on(x3,x4) & on(x4,x5) & n_side(x5) & of(x5,x1) & n_thing(x1) & (exists x8.(n_bike(x4) & of(x4,x8) & n_catch(x8)) | (n_bike(x4) & n_motocross(x4))) & n_looker(x3) & after(e1,x2) & n_spill(x2) & Actor(e1,x1) & v_event(e1))
exists e1 x1 x2.(on(e1,x2) & n_side(x2) & of(x2,x1) & n_thing(x1) & Actor(e1,x1) & v_lay(e1) & n_motorcycle(x1))