The boy is skateboarding on the bench by the fence.
The person is on his skateboard.
on his skateboard continues the act of skateboarding
exists e1 x1 x2 x3.(n_fence(x3) & n_bench(x2) & n_boy(x1) & by(e1,x3) & on(e1,x2) & Actor(e1,x1) & v_skateboard(e1))
exists p1 x1 x2.(n_skateboard(x2) & of(x2,x1) & n_male(x1) & n_person(x1) & on(x1,x2))