最新提问
我的动态
登录后查看动态
题目内容
There are 10 different books available to a librarian for purchase, each for the same price, but the librarian has only enough money to purchase 9 of them. How many different collections of 9 books are there that can be selected from the 10 books?
B显示答案
· 相关考点
6.3.4 组合
6.3.4 组合
以上解析由 考满分老师提供。