This person sits behind platters full of food with their elbow resting on their knee.
The person is selling platters of food, but has no customers.
Just because a person sits behind platters doesn't mean this person is selling platters.
exists e1 e2 s1 x1 x2 x3 x4 x5 x6 x7.(n_knee(x7) & of(x7,x1) & n_thing(x1) & n_thing(x1) & n_elbow(x5) & of(x5,x1) & n_person(x1) & with(e1,x5) & on(e2,x7) & Actor(e2,x6) & v_rest(e2) & (x5 = x6) & behind(e1,x2) & of(s1,x4) & n_food(x4) & Theme(s1,x3) & a_full(s1) & (x2 = x3) & n_platter(x2) & Actor(e1,x1) & v_sit(e1))
exists e1 x1 x2 x3.(n_person(x1) & -exists e2 x4.(Theme(e2,x4) & Actor(e2,x1) & v_have(e2) & n_customer(x4)) & Theme(e1,x2) & Actor(e1,x1) & v_sell(e1) & of(x2,x3) & n_food(x3) & n_platter(x2))