Git is a distributed version control system.
Git is a free software distributed under the GPL.（错误改了）
Git has a mutable index called stage.
Git tracks changes of files.
I use github.
Create a new branch  is quick and simple.
I work at dev branch,还需要一天时间才能提交。但现在有一个BUG需要立即修改。
我需要再学习一次stash.
我发现了一个错误。需要修改。