A group of people are standing in front of some stores.
There is a boy playing in the park
"A boy" and "a group of people" are different amounts of people.  Playing and standing are different actions.  There are no stores at a park.
exists e1 x1 x2 x3 x4.(in(e1,x3) & of(x3,x4) & n_store(x4) & n_front(x3) & Actor(e1,x1) & v_stand(e1) & of(x1,x2) & n_people(x2) & n_group(x1))
exists p1 x1 x4.(n_park(x4) & exists x2 x3.((x1 = x2) & in(x2,x4) & n_playing(x2) & of(x2,x3) & n_boy(x3)))