The child in the green shirt is on a machine with wheels.
A person is using a machine.
A child is a person.  On a machine is another way of saying using a machine.
exists p1 s1 x1 x2.(n_shirt(x2) & a_green(s1) & Theme(s1,x2) & n_child(x1) & exists x3 x4.(on(x1,x3) & with(x3,x4) & n_wheel(x4) & n_machine(x3)) & in(x1,x2))
exists e1 x1 x2.(Theme(e1,x2) & Actor(e1,x1) & v_use(e1) & n_machine(x2) & n_person(x1))