A girl sitting on a bench.
A girl is sitting by herself on a bench in the park.
Sitting on a bench does not necessarily mean she is by herself.
exists e1 x1 x2 x3.(a_topic(x1) & on(e1,x3) & n_bench(x3) & Actor(e1,x2) & v_sit(e1) & (x1 = x2) & n_girl(x1))
exists e1 x1 x2 x3.(n_park(x3) & in(e1,x3) & on(e1,x2) & n_bench(x2) & by(e1,x1) & n_female(x1) & Actor(e1,x1) & v_sit(e1) & n_girl(x1))