A snowboarder riding down a railing.
A snowboarder on a snowboard
snowboarder is on his snowboard
exists e1 s1 x1 x2 x3.(a_topic(x1) & a_down(s1) & Manner(e1,s1) & Theme(e1,x3) & Actor(e1,x2) & v_ride(e1) & n_railing(x3) & (x1 = x2) & n_snowboarder(x1))
exists x1 x2.(a_topic(x1) & on(x1,x2) & n_snowboard(x2) & n_snowboarder(x1))