In mathematics, combination is a selection of items from a collection, such that (unlike permutations) the order of selection does not matter

走进命令行的世界

Git is a distributed version control system

Markdown是一种可用文本编辑器编写的标记语言，通过简单的语法，可以使文本具有一定的格式

你瞧这些白云聚了又散，散了又聚，人生离合，亦复如斯