Two men t-shirts are working on a mechanical device.
the two men are mechanics
Working on a mechanical device does not imply they are mechanics.
exists e1 s1 x1 x2 x3.(on(e1,x3) & n_device(x3) & a_mechanical(s1) & Theme(s1,x3) & Actor(e1,x1) & v_work(e1) & n_t-shirt(x1) & of(x1,x2) & n_man(x2) & card_eq_2(x1))
exists p1 x1.(n_man(x1) & card_eq_2(x1) & exists x2.((x1 = x2) & n_mechanic(x2)))