0, is studied. It has been known that there exists a positive number Λ such that if λ>Λ, then the problem has no positive solution; if λ Λ, then there exists a maximal solution; and for sufficiently small λ (<Λ), the problem has at least two solutions. In this article, it is shown that if λ<Λ, then there exist at least two positive solutions, via the variational method.