A man is operating a piece of machinery.
The piece of machinery is being operated by a man.
"A piece of machinery is being operated" is a passive way to say "Operating a piece of machinery."
exists e1 x1 x2 x3.(Theme(e1,x2) & Actor(e1,x1) & v_operate(e1) & of(x2,x3) & n_machinery(x3) & n_piece(x2) & n_man(x1))
exists e1 x1 x2 x3.(n_piece(x1) & Actor(e1,x3) & n_man(x3) & Theme(e1,x1) & v_operate(e1) & of(x1,x2) & n_machinery(x2))