国家教育部考试中心 2 0 0 0年普通高考数学科试题分析报告说 :“控制计算量 ,避免繁琐运算 .一些貌似有较长运算过程的试题都有不同的解题思维层次 .”本文拟通过一例 ,说明我们对这句话的理解 .例　等差数列 {ａｎ}中 ,前ｍ项和Ｓｍ =Ｓｎ(ｍ≠ｎ) ,求Ｓｍ+ｎ 的值 .解法 1　 According to the analysis report of the examination questions of the National College Entrance Examination for the Ministry of Education Examination Center in 2000, “Controlling the amount of calculations to avoid cumbersome calculations. Some questions that seem to have a longer calculation process have different levels of problem-solving thinking.” An example to illustrate our understanding of this sentence. In the case of the equal-difference sequence {an}, the first m terms and Sm = Sn(m≠n), find the value of Sm+n. Solution 1