Circle actions on 3-manifolds (Ex)

Let $M$$<wikitex>; Let $M$ be a closed orientable $-manifold with a proper $S^1$-action. Is $M$ a Seifert fibered manifold? </wikitex> [[Category:Exercises]] [[Category:Exercises without solution]]M$ be a closed orientable $3$$3$-manifold with a proper $S^1$$S^1$-action. Is $M$$M$ a Seifert fibered manifold?