the two couples are chatting by the bus.
The two couples are sleep at the bus stop.
People cannot be chatting and asleep at the same time.
exists e1 x1 x2.(n_bus(x2) & n_couple(x1) & card_eq_2(x1) & by(e1,x2) & Actor(e1,x1) & v_chat(e1))
exists p1 x1 x2 x3.(n_stop(x2) & of(x2,x3) & n_bus(x3) & n_couple(x1) & card_eq_2(x1) & at(p1,x2) & exists x4.((x1 = x4) & n_sleep(x4)))