1 passive necessity
2 sequencing first，after，later，having done，before，when，once
3 useful language ： 1 this preserves them and makes them ready to be‘’‘’‘’‘
2 this way of （this n of ’‘’‘’）
开头： to---- 把目的说一下
小细节： 1 对名词的修饰+ the
2 动词的单复数 很重要
开头模板：
In contemporary world, what is quite natural to be seen is that a majority of people had seen / done .....
How it works ? the follow process is liable to account for it