Two people are reading something while sitting on a bench.
Two people seated on a bench while reading.
Two people are reading  while sitting on a bench can be rephrased as two people seated on a bench while reading.
exists e2 e1 x1 x2 x3.(while(e1,e2) & on(e2,x3) & n_bench(x3) & Actor(e2,x1) & v_sit(e2) & Theme(e1,x2) & Actor(e1,x1) & v_read(e1) & n_thing(x2) & n_people(x1) & card_eq_2(x1))
exists e1 x1 x2 x3 x4.(a_topic(x1) & while(e1,x4) & n_read(x4) & on(e1,x3) & n_bench(x3) & Theme(e1,x2) & v_seat(e1) & (x1 = x2) & n_people(x1) & card_eq_2(x1))