A girl and boy sit on a fence.
A girl and boy sit on a fence waiting for their friend.
There may not be any waiting taking place.
exists e1 x1 x2 x3 x4.(on(e1,x4) & n_fence(x4) & Actor(e1,x1) & v_sit(e1) & n_boy(x3) & n_girl(x2) & subset_of(x3,x1) & subset_of(x2,x1))
exists e1 e2 x1 x2 x3 x4 x5.(for(e1,e2) & for(e2,x5) & n_friend(x5) & of(x5,x2) & n_thing(x2) & Actor(e2,x1) & v_wait(e2) & on(e1,x4) & n_fence(x4) & Actor(e1,x1) & v_sit(e1) & n_boy(x3) & n_girl(x2) & subset_of(x3,x1) & subset_of(x2,x1))