In this paper

we aim to present a new proof for the Theorem:if the continuous and almost open linear mapping from the local convex space E to arbitrary local convex space is always open mapping

then E is complete completeness.Under the condition of separated locally convex space

making use of the properties that the range of conjugate mappings of continuous open linear mappings is weakly closed

we prove that if E is separated locally convex space

and the continuous and almost open linear mapping from the local convex space E to arbitrary local convex space is always open mapping

then E is complete completeness.