盒子里有红色、绿色、黄色、蓝色乒乓球各1个，现要从中取出2个球，共有_1种不同取法，若要从中取出3个球，又有_2种不同的取法．_刷题宝

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盒子里有红色、绿色、黄色、蓝色乒乓球各1个，现要从中取出2个球，共有____种不同取法，若要从中取出3个球，又有____种不同的取法．

上一题下一题 0.0难度选择题更新时间:2018-11-20 02:58:58

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6,4

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