A man in a green protective apron is using a weed-eater.
A man with no apron is smoking a pipe.
One is either wearing a green protective apron or wearing no apron. One who is using a weed-eater is usually not smoking a pike.
exists e1 s1 s2 x1 x2 x3.(Theme(e1,x3) & Actor(e1,x1) & v_use(e1) & n_weed-eater(x3) & in(x1,x2) & n_apron(x2) & a_protective(s2) & Theme(s2,x2) & a_green(s1) & Theme(s1,x2) & n_man(x1))
exists x1.(-exists e1 x2 x3.(Theme(e1,x3) & Actor(e1,x1) & v_smoke(e1) & n_pipe(x3) & with(x1,x2) & n_apron(x2)) & n_man(x1))