Employing the nonlinear gyrokinetic equations,we have reexamined the parametric decay instabilities and the nonlinear excitations of zonal flows by the kinetic Alfvén waves.In the case of parametric decays,a dispersion relation valid for arbitrary k(⊥) ρi has been derived.Here,k⊥ is the wave number perpendicular to the confining magnetic field and ρi is the ion Larmor radius.