A person rides a four-wheeler in the air.
A person is riding a motorcycle.
A four-wheeler and an motorcycle are different vehicles. You can't ride them at the same time.
exists e1 x1 x2 x3.(n_air(x3) & in(e1,x3) & Theme(e1,x2) & Actor(e1,x1) & v_ride(e1) & n_four-wheeler(x2) & n_person(x1))
exists e1 x1 x2.(Theme(e1,x2) & Actor(e1,x1) & v_ride(e1) & n_motorcycle(x2) & n_person(x1))