A teenager is skateboarding in an empty park.
A teenager rides a skateboard on the way to a friend's house.
A teenager is skateboarding doesn't imply that he is on the way to a friend's house.
exists e1 s1 x1 x2.(in(e1,x2) & n_park(x2) & a_empty(s1) & Theme(s1,x2) & Actor(e1,x1) & v_skateboard(e1) & n_teenager(x1))
exists e1 x1 x2 x3 x4 x5.(n_way(x3) & on(e1,x3) & to(x3,x5) & n_house(x5) & of(x5,x4) & n_friend(x4) & Theme(e1,x2) & Actor(e1,x1) & v_ride(e1) & n_skateboard(x2) & n_teenager(x1))