序列 s1={1,3,4,5,6,7,7,8,1}、s2={3,5,7,4,8,2,9,5,1},它们的最长公共子序列是: A. {3,5,7,8,1}B. {3,4,5,7,8}C. {5,7,8}D. {3,5,7,9,1} 正确答案:A