题目

将写有1，2，3，4，5的5张卡片分别放入标有1，2，3，4，5的5个盒子内，每个盒里放且只放1张卡片，那么2号卡片不在2号盒内且4号卡片不在4号盒内的放法数等于（    ）A.42                   B.72                  C.78                   D.120 答案：解析：用间接法可得-2+=78.故选C.答案：CIf there       no buying and selling of animals, there      no killing in natureA.is; will heB.will be; will beC.is; isD.will be; is