a young girl stands on one leg.
A young girl standing
Just because a young girl is standing it does not mean she is on both legs.
exists e1 s1 x1 x2.(on(e1,x2) & n_leg(x2) & card_eq_1(x2) & Actor(e1,x1) & v_stand(e1) & n_girl(x1) & a_young(s1) & Theme(s1,x1))
exists s1 x1 x2.(a_topic(x1) & n_standing(x1) & of(x1,x2) & n_girl(x2) & a_young(s1) & Theme(s1,x1))