A young boy holds a welders mask in front of his face with one hand while welding with the other.
A boy is wearing a mask and working.
The boy holds a welders mask in front of his face so the boy is wearing a mask.  Working is a rephrasing for while welding.
exists e2 e1 s1 x1 x2 x3 x4 x5 x6 x7.(n_other(x7) & while(e1,e2) & with(e2,x7) & Actor(e2,x1) & v_weld(e2) & with(e1,x6) & n_hand(x6) & card_eq_1(x6) & in(e1,x4) & of(x4,x5) & n_face(x5) & of(x5,x1) & n_male(x1) & n_front(x4) & Theme(e1,x2) & Actor(e1,x1) & v_hold(e1) & n_mask(x2) & of(x2,x3) & n_welder(x3) & n_boy(x1) & a_young(s1) & Theme(s1,x1))
exists p1 s1 x1 x2 x3.(n_thing(x2) & Theme(s1,x3) & a_working(s1) & (x2 = x3) & n_thing(x1) & exists e1 x4 x5.(Theme(e1,x5) & Actor(e1,x4) & v_wear(e1) & n_mask(x5) & n_boy(x4)) & that(x1,p1))