Concerning the Center of the System(x) =h(y)-F(x),y=-g(x)
关于系统(x)=h(y)-F(x),(y)=-g(x) 的中心

In this paper, for the origin of the generalized Lienard systems to be the global centerand the local center we give the necessary and sufficient conditions and sufficient conditionsrespectively. The results of papers 1-6] are thus extended and improved.