  The angular and energy distributions of the final lepton in e ebar t tbar -->
l^{+-} X at next linear colliders (NLC) are analyzed a model-independent way
for arbitrary longitudinal beam polarizations as sensitive tests of possible
anomalous top-quark couplings. The angular-energy distribution is expressed as
a combination of independent functions of the angle and the energy, where each
anomalous parameter is the coefficient of an individual term. Every parameter
could be thereby determined simultaneously via the optimal-observable
procedure. On the other hand, anomalous tbW couplings totally decouple from the
angular distribution, which enables us to study t-tbar-gamma/Z couplings
exclusively.
