Several birds flying in front of trees.
Birds are eating off the ground.
Birds cannot be flying and eating simultaneously.
exists e1 s1 x1 x2 x3 x4.(a_topic(x1) & in(e1,x3) & of(x3,x4) & n_tree(x4) & n_front(x3) & Actor(e1,x2) & v_fly(e1) & (x1 = x2) & n_bird(x1) & a_several(s1) & Theme(s1,x1))
exists e1 x1 x2.(n_ground(x2) & off(e1,x2) & Actor(e1,x1) & v_eat(e1) & n_bird(x1))