People looking at the water.
People are looking at a tree.
A tree is not found in the water.
exists e1 x1 x2.(n_water(x2) & at(e1,x2) & Actor(e1,x1) & v_look(e1) & n_people(x1))
exists e1 x1 x2.(at(e1,x2) & n_tree(x2) & Actor(e1,x1) & v_look(e1) & n_people(x1))