Skateboard rider balancing on a rock on his skateboard.
A skateboarder is on his board.
A board that skateboarder riders use are skateboards. Skateboard riders balance their skateboards on a rock.
exists e1 x1 x2 x3 x4 x5.(a_topic(x1) & on(e1,x4) & on(x4,x5) & n_skateboard(x5) & of(x5,x1) & n_male(x1) & n_rock(x4) & Actor(e1,x3) & v_balance(e1) & (x1 = x3) & n_rider(x1) & (x1 = x2) & ne_nam_skateboard(x2))
exists p1 x1 x2.(on(x1,x2) & n_board(x2) & of(x2,x1) & n_male(x1) & n_skateboarder(x1))