  We consider a model of Fermi-Bose mixture with strong hard-core repulsion
between particles of the same sort and attraction between particles of
different sorts. In this case, besides the standard anomalous averages of the
type $<b>$; $<bb>$ and $<cc>$, a pairing between fermion and boson of the type
$bc$ is possible. This pairing corresponds to a creation of composite fermions
in the system. At low temperatures and equal densities of fermions and bosons
composite fermions are further paired in quartets. Our investigations are
important for high-$T_c$ superconductors and in connection with recent
observation of weakly bound dimers in magnetic traps at ultralow temperatures.
