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有一次,班上两名同学为一道题争论不下,拿来让我评判,题目是这样的:“有甲、乙、丙三只布熊,A、B两种墨镜。现在给每个布熊配一副墨镜,有()种不同的选配方法。”粗一看,以为就是用学生刚学的“搭配规律”来算,先选布熊,有3种可能,再选墨镜,有2种可能,3×2=6(种),如果这样做,那就大错特错了!那么正确的答案又是什么呢?我们先来剖析一下。一、本题与教材例题很相似,但题目要求却不同
Once, two students in the class argued for a question, used to let me judge, the title is this: “There are A, B, C three bears, A, B two kinds of sunglasses Now give each cloth Bear with a pair of sunglasses, there are () kinds of different matching methods. ”“ Crude look, thinking is that students just learned ”with the law " to count, choose cloth first, there are 3 possibilities, re-election Sunglasses, there are two possibilities, 3 × 2 = 6 (species), if you do that, then it is wrong! Then the correct answer is what? Let us analyze. First, the questions and teaching examples are similar, but the subject requirements are different