as的几种用法：

1.做连词，固定搭配as……as，意思是“和……一样”；

2.做连词，表示“当……的时候”；

3.做连词，表示“因为”

4.做连词，表示“尽管”等。

1.as做连词，固定搭配as……as，意思是“和……一样”例句：

My sister is as tall as me.

我姐姐和我一样高。

He runs as fast as me/I. 

他和我跑得一样快。

She is as beautiful as me/I. 

她和我一样漂亮。

Being a mother isn't as bad as I thought at first!

做一位母亲并不像我当初想的那样糟！

2.as做连词，引导时间状语从句，意思是“当……的时候”

例句：

My mother was cooking fish as I arrived home.

当我到家的时候，我妈妈正在做鱼。

I was always hard up as a student. 

我当学生时总是很拮据。

The crowd cheered as she went up the steps to the bandstand. 

当她走上演奏台的台阶时，人群欢呼起来。

All the jury's eyes were on him as he continued.

所有陪审员的目光在他继续下去时都集中在了他身上。

3.as做连词，引导原因状语从句，意思是“因为”

例句：

As rain has fallen, the air is cooler. 

因为下过雨，所以空气比较凉爽。

Enjoy the first hour of the day. This is important as it sets the mood for the rest of the day.

享受一天中的第一个小时。这很重要，因为这第一个小时决定当天其余时间的情绪。

4.as做连词，引导让步状语从句，意思是“虽然，尽管”

例句：

Young as he is, he has been one of the most famous painters in our country.