阿钟 发表于 2013-10-20 14:25
应该是S compact => f(S) compact.
然后inverse of open is always open, inverse of close is always ...
这个选项不对吧。考虑 stereographic projection X 是riemann surface Y 是complex plane S 是包含rieman surface 球顶的一个compact 邻域,那它映到 complex plane 无穷了 是closed but not bounded。A选项我举不出反例