A boy is doing a stunt with his skateboard.
The boy is on his bicycle.
One cannot be on a skateboard and bicycle simultaneously.
exists e1 x1 x2 x3.(Theme(e1,x2) & Actor(e1,x1) & v_do(e1) & with(x2,x3) & n_skateboard(x3) & of(x3,x1) & n_male(x1) & n_stunt(x2) & n_boy(x1))
exists p1 x1 x2.(n_bicycle(x2) & of(x2,x1) & n_male(x1) & n_boy(x1) & on(x1,x2))