Two people stand before an ambulance.
Two people are in front of an ambulance
in front is a rephrasing of stand before.
exists e1 x1 x2.(before(e1,x2) & n_ambulance(x2) & Actor(e1,x1) & v_stand(e1) & n_people(x1) & card_eq_2(x1))
exists p1 x1.(exists x2 x3.(in(x1,x2) & of(x2,x3) & n_ambulance(x3) & n_front(x2)) & n_people(x1) & card_eq_2(x1))