Two construction workers sitting on some pipes while one waves, obscuring his face.
The workers are wearing helmets.
Construction workers does not imply wearing helmets.
exists e1 e2 x1 x2 x3 x4 x5 x6 x7.(Theme(e2,x7) & Actor(e2,x5) & v_obscure(e2) & n_face(x7) & of(x7,x2) & n_male(x2) & n_worker(x5) & of(x5,x6) & n_construction(x6) & card_eq_2(x5) & while(e1,x4) & n_wave(x4) & card_eq_1(x4) & on(e1,x3) & n_pipe(x3) & Actor(e1,x1) & v_sit(e1) & n_worker(x1) & of(x1,x2) & n_construction(x2) & card_eq_2(x1))
exists e1 x1 x2.(n_worker(x1) & Theme(e1,x2) & Actor(e1,x1) & v_wear(e1) & n_helmet(x2))