高考中的排列组合问题往往立意新颖、构思精巧,解法灵活,能较好地考查学生分析问题和解决问题的能力,倍受命题者的青睐.考题中我们发现有一类分配问题,因为条件的细微差异,结果大相径庭,学生不易掌握,极为苦恼.这类问题一般可抽象为将一定数量的球按要求往一定数量的盒子里面放,我们通常称之为“球—盒”问题.下面我们就以一道较简单的习题为例,通过对8个姊妹题的解答分析,揭 The permutations and combinations in the college entrance examination tend to be innovative, sophisticated ideas, flexible solutions, students can better examine the ability to analyze and solve problems, much of the favored by the proponents.Examination we found a class of distribution problems, because the subtle conditions Differences, the results are very different, students are not easy to grasp, very distressed.This kind of problem can be generally abstract as a number of balls as required to a certain number of boxes inside, we often call "ball - box Take a relatively simple exercise as an example, through analysis of answers to eight sisters’ questions