题目

将10个相同的小球放入编号分别为1,2,3,4的四个盒子中,要求每个盒子中的球数不少于一个,求放法总数是____________. 答案:84;           Nobody had the idea whether they ________ for the fuel left. [  ] A.cameB.have come C.will comeD.were coming
数学 试题推荐