People sitting in an airplane.
People are sitting on a train.
A train is not an airplane.
exists e1 x1 x2 x3.(a_topic(x1) & in(e1,x3) & n_airplane(x3) & Actor(e1,x2) & v_sit(e1) & (x1 = x2) & n_people(x1))
exists e1 x1 x2.(on(e1,x2) & n_train(x2) & Actor(e1,x1) & v_sit(e1) & n_people(x1))