Two people are walking along a long cannon on a tank.
Two people are looking at a tank before buying it.
Walking along the cannon doesn't explain that they are looking to buy the tank.
exists e1 s1 x1 x2 x3.(on(e1,x3) & n_tank(x3) & along(e1,x2) & n_cannon(x2) & a_long(s1) & Theme(s1,x2) & Actor(e1,x1) & v_walk(e1) & n_people(x1) & card_eq_2(x1))
exists e2 e1 x1 x2.(before(e1,e2) & Theme(e2,x2) & Actor(e2,x1) & v_buy(e2) & n_thing(x2) & at(e1,x2) & n_tank(x2) & Actor(e1,x1) & v_look(e1) & n_people(x1) & card_eq_2(x1))