The students sitting on the grass are eating a lunch from a red backpack.
People are eating lunch at school.
Just because they are students doesn't mean they are at school.
exists e1 e2 s1 x1 x2 x3 x4 x5.(n_grass(x3) & n_student(x1) & Theme(e2,x4) & Actor(e2,x1) & v_eat(e2) & from(x4,x5) & n_backpack(x5) & a_red(s1) & Theme(s1,x5) & n_lunch(x4) & on(e1,x3) & Actor(e1,x2) & v_sit(e1) & (x1 = x2))
exists e1 x1 x2 x3.(at(e1,x3) & n_school(x3) & Theme(e1,x2) & Actor(e1,x1) & v_eat(e1) & n_lunch(x2) & n_people(x1))