We construct the Drinfeld twists (factorizing F-matrices) for the
supersymmetric t-J model. Working in the basis provided by the F-matrix (i.e.
the so-called F-basis), we obtain completely symmetric representations of the
monodromy matrix and the pseudo-particle creation operators of the model. These
enable us to resolve the hierarchy of the nested Bethe vectors for the
gl(2∣1) invariant t-J model.Comment: 23 pages, no figure, Latex file, minor misprints are correcte