Continuity of the Complex Monge-Ampere operator on compact Kahler manifolds

We prove several approximation theorems of the complex Monge-Ampere operator on a compact Kahler manifold. As an application we prove the Cegrell type theorem on a complete description of the range of the complex Monge-Ampere operator in the class of omega-plurisubharmonic functions with vanishing complex Monge-Ampere mass on all pluripolar sets. As a by-product we obtain a stability theorem of solutions of complex Monge Ampere equations.