couple at a dinner table.
A couple eating dinner
Being at a table does not imply eating dinner.
exists x1 x2 x3.(a_topic(x1) & at(x1,x2) & n_table(x2) & of(x2,x3) & n_dinner(x3) & n_couple(x1))
exists x1 x2 x3.(a_topic(x1) & n_dinner(x1) & of(x1,x3) & n_eating(x3) & of(x1,x2) & n_couple(x2))