目前在一些中学不同程度地存在一个问题:学生学习《立体几何》时,空间想象能力差,对课本上描述的事实,不能很好地领会,也不能举出生活中的实例,更不知如何去动手“操作”.这里的“操作”,指的是按题中给定的条件去“做一做”,“摆一摆”,目的是探索解决问题的方法.学生要学好立 At present, in some secondary schools, there is a problem to a certain degree. When students study “Three-Dimensional Geometry,” students have poor spatial imagination. They cannot understand the facts described in textbooks, and cannot give examples in life. They do not know how to go. Hands-on “operation”. Here “operation” means referring to the conditions given in the question to “do one” and “put a pendulum” in order to explore ways to solve the problem. Students should learn how to