A man is singing into a microphone.
A man is performing on stage.
A man who is singing on a microphone is not necessarily on a stage.
exists e1 x1 x2.(into(e1,x2) & n_microphone(x2) & Actor(e1,x1) & v_sing(e1) & n_man(x1))
exists e1 x1 x2.(on(e1,x2) & n_stage(x2) & Actor(e1,x1) & v_perform(e1) & n_man(x1))