请教一道SAT数学题,为2010年10月section8的16题.要解析 题目为The integers 1 through 6 appear on the six faces of a cube,one on each face.If three such cubes are rolled,what is the probability that the sum of the numbers on the top faces is 17 or 18? 选项为: A:1/108 B:1/54 C:1/27 D:1/18 E:1/16 正确选项为B,但我认为选A