A person riding a bike in a parking lot.
A person is riding a skateboard.
There can be either a bike or a skateboard.
exists e1 x1 x2 x3 x4 x5.(a_topic(x1) & in(e1,x4) & n_lot(x4) & of(x4,x5) & n_parking(x5) & Theme(e1,x3) & Actor(e1,x2) & v_ride(e1) & n_bike(x3) & (x1 = x2) & n_person(x1))
exists e1 x1 x2.(Theme(e1,x2) & Actor(e1,x1) & v_ride(e1) & n_skateboard(x2) & n_person(x1))