  The formulae of particle current as well as spin- and angular momentum
currents are studied for most spin-orbit coupling (SOC) systems. It is shown
that the conventional expression of currents in some literatures are not
complete for some SOC systems. The particle current in Dresselhaus system must
have extra terms in additional to the conventional one, but no extra term for
Rashba, Luttinger model. Further more, we also prove that the extra terms of
total angular momentum appear in Rashba current in addition to conventional
one.
