The research on oscillation for general mechanical and electronic vibration mathematical models，which are usually functional differential equations

has important implications in both theory and practice. The oscillation of third-order nonlinear neutral functional differential equations with continuous distributed delay and damping terms is studied. By using the generalized Riccati transformation

H-function and integral averaging technique

some new sufficient conditions which insure that any solution of such equation oscillates or converges to zero are established. The corresponding known results are extended and improved.