Boy playing with a truck.
The boy is sitting in a toy truck.
A boy playing with a truck is not necessarily sitting in a toy truck.
exists x1 x2 x3.(a_topic(x1) & with(x1,x3) & n_truck(x3) & n_playing(x1) & (x1 = x2) & ne_nam_boy(x2))
exists e1 x1 x2 x3.(n_boy(x1) & in(e1,x2) & n_truck(x2) & of(x2,x3) & n_toy(x3) & Actor(e1,x1) & v_sit(e1))