The helmeted boy is doing a stunt on a skateboard.
A boy is riding his bike.
A boy is either on a skateboard or riding his bike he can't do both things simultaneously.
exists e1 s1 x1 x2 x3.(n_boy(x1) & a_helmeted(s1) & Theme(s1,x1) & Theme(e1,x2) & Actor(e1,x1) & v_do(e1) & on(x2,x3) & n_skateboard(x3) & n_stunt(x2))
exists e1 x1 x2.(Theme(e1,x2) & Actor(e1,x1) & v_ride(e1) & n_bike(x2) & of(x2,x1) & n_male(x1) & n_boy(x1))