立体几何中的排列组合问题在近几年的高考数学试题中出现的频率较高,且常考常新.解决这类问题不仅要具备排列组合的有关知识,而且还要具备较强的空间想象能力,因而是一类既富思考情趣,又融众多知识和技巧于一体且综合性强、灵活性高、难度颇大的挑战性问题.解决这类问题的关键是明确形成几何图形的元素,并与排列组合形成对应关系,转化为 The problems of permutation and combination in the three-dimensional geometry appear frequently in the mathematics questions of the college entrance examination in recent years, and they often test the new ones. To solve such problems, it is necessary not only to arrange the relevant knowledge, but also to have a strong spatial imagination. Competence, therefore, is a kind of challenging problem that is rich in thinking about taste, but also integrates many knowledge and skills, and is comprehensive, flexible, and difficult. The key to solving this kind of problem is to clearly define the elements of geometric figures. And form a correspondence relationship with the permutation and combination, and translate into