In this short paper, we firstly give a short proof of Birkhoff-Kakutani Theorem by Moore metrizable Theorem. Then we pro......

用反证法及构造法，证明了第一可数正规-闭空间、第一可数正规极大空间、第一可数正规极小空间、第一可数正规弱紧空间的等价性．......