  Screening of the electric field of a test charge by monolayer and
double-layer composite fermion systems is considered. It is shown that the
electric field of the test charge is partly screened at distances much large
then the magnetic length. The value of screening as a function of the distance
depends considerably on the filling factor. The effect of variation of the
value of screening in the double-layer system upon a transition to a state
described by the Halperin wave function is determined.
