i.e. e.g. etc.

都是拉丁语的简写

i.e. that is  　　  “My friend david is a vegan, i.e. he only eats ...”

e.g. for example

etc. 　　　　　　and other similar things. It is used to avoid giving a complete list

 (linux 系统中就有一个叫etc的目录 就是用来存一些零零碎碎的文件)