Several men are tinkering with radio controlled items.
Several men were working on their radio controlled cars.
Just because the men are tinkering does not mean they are working.
exists e1 e2 s1 x1 x2 x3.(with(e1,x2) & n_item(x2) & Theme(e2,x2) & v_control(e2) & of(x2,x3) & n_radio(x3) & Actor(e1,x1) & v_tinker(e1) & n_man(x1) & a_several(s1) & Theme(s1,x1))
exists e1 e2 s1 x1 x2 x3.(on(e1,x2) & n_car(x2) & Theme(e2,x2) & v_control(e2) & of(x2,x3) & n_radio(x3) & of(x2,x1) & n_thing(x1) & Actor(e1,x1) & v_work(e1) & n_man(x1) & a_several(s1) & Theme(s1,x1))