The boy is cutting the grass.
The boy cut the grass for allowance.
Not all boys cutting grass are doing so for allowance
exists e1 x1 x2.(n_grass(x2) & n_boy(x1) & Theme(e1,x2) & Actor(e1,x1) & v_cut(e1))
exists e1 x1 x2 x3.(n_grass(x2) & n_boy(x1) & Theme(e1,x2) & Actor(e1,x1) & v_cut(e1) & for(x2,x3) & n_allowance(x3))