A police officer riding a motorcycle.
There is a firefighter in a truck.
Either the subject is a firefighter or police officer. He is either riding a motorcycle or in a truck.
exists e1 x1 x2 x3 x4.(a_topic(x1) & Theme(e1,x4) & Actor(e1,x3) & v_ride(e1) & n_motorcycle(x4) & (x1 = x3) & n_officer(x1) & of(x1,x2) & n_police(x2))
exists p1 x1 x2.(in(p1,x2) & n_truck(x2) & exists x3.((x1 = x3) & n_firefighter(x3)))