A man is working on steel.
The man is a construction worker.
Working on steel does not imply construction work, more likely it implies a steel mill worker.
exists e1 x1 x2.(on(e1,x2) & n_steel(x2) & Actor(e1,x1) & v_work(e1) & n_man(x1))
exists p1 x1.(n_man(x1) & exists x2 x3.((x1 = x2) & n_worker(x2) & of(x2,x3) & n_construction(x3)))