Men sitting on an army tank.
Some men are sitting on a tank.
An army tank is a tank.
exists e1 x1 x2 x3 x4.(a_topic(x1) & on(e1,x3) & n_tank(x3) & of(x3,x4) & n_army(x4) & Actor(e1,x2) & v_sit(e1) & (x1 = x2) & n_man(x1))
exists e1 x1 x2.(on(e1,x2) & n_tank(x2) & Actor(e1,x1) & v_sit(e1) & n_man(x1))