A boy is standing on a sidewalk with his bike.
The boy is riding a skateboard.
A bike and a skateboard are two different things.
exists e1 x1 x2 x3.(with(e1,x3) & n_bike(x3) & of(x3,x1) & n_male(x1) & on(e1,x2) & n_sidewalk(x2) & Actor(e1,x1) & v_stand(e1) & n_boy(x1))
exists e1 x1 x2.(n_boy(x1) & Theme(e1,x2) & Actor(e1,x1) & v_ride(e1) & n_skateboard(x2))