A man riding a dirt bike
The man is in a car.
The man is either in a car or riding on a dirt bike. These are two different vehicles.
exists e1 x1 x2 x3 x4.(a_topic(x1) & Theme(e1,x3) & Actor(e1,x2) & v_ride(e1) & n_bike(x3) & of(x3,x4) & n_dirt(x4) & (x1 = x2) & n_man(x1))
exists p1 x1.(n_man(x1) & exists x2.(in(x1,x2) & n_car(x2)))