A man with a gas mask and goggles on his head.
The man is participating in a drill.
A man with a gas mask and goggles on his head does not necessarily participating in a drill.
exists x1 x2 x3 x4 x5 x6.(a_topic(x1) & with(x1,x2) & subset_of(x5,x2) & on(x5,x6) & n_head(x6) & of(x6,x1) & n_male(x1) & n_goggles(x5) & subset_of(x3,x2) & n_mask(x3) & of(x3,x4) & n_gas(x4) & n_man(x1))
exists e1 x1 x2.(n_man(x1) & in(e1,x2) & n_drill(x2) & Actor(e1,x1) & v_participate(e1))