A girl is performing a skateboarding maneuver.
A girl is riding a bike.
One can not be skateboarding and riding a bike simultaneously.
exists e1 e2 x1 x2.(Theme(e2,x2) & Actor(e2,x1) & v_perform(e2) & n_maneuver(x2) & Actor(e1,x2) & v_skateboard(e1) & n_girl(x1))
exists e1 x1 x2.(Theme(e1,x2) & Actor(e1,x1) & v_ride(e1) & n_bike(x2) & n_girl(x1))