1. as作介词

　　(1)当作+表身份/地位/人的特征名词作宾语

　　举例：

　　Although he had signed a pledge of abstinence asab adolescent, Amy was 40 years old before she chose to become a temperance activist.

　　He came Shanghai as a tourist.

　　In Evolution time,women are considered as the means of bringing peace and good sense to a war-torn word.

　　(2)做介词常跟如下这些词连用：be seen as; regard...as ,think...as,consider...as

　　2. as做连词

　　(1)表示时间：随着...;表示两个同时正在演变的情况

　　举例：

　　As more and more people invest their money in savings certificates or money-market funds in order to earn higher interest,theey are abandoning traditional low-interest investment such as passbook accounts and life insurance policies

　　(2) 表原因：因为,..

　　举例：‍‍‍

　　I treat my children well as they had done the work well‍

　　(3) 表示让步：虽然，既然...‍match‍

　　举例：

　　Warm as it was, we stayed home.

　　Try as she would, he could not lift the rock

　　(4) 表示动作的方式;像...

　　举例：

　　you need to do as i tell you to.

　　as做连词时相当于when，because;

　　3. as做比较

　　(1) 可做引导定语从句的关系词讲：可以等同于关系代词：表人的whom,who,that,which,when,where

　　举例：

　　I like Jay Zhou as most young people do.

　　I will go the same time as you do.

　　The same teacher as taught my uncle is teaching my son now.

　　(2) 也可引导非限定性定语从句

　　举例：

　　A report by James, recorded in the same year as the earthquake happened, tells that there were nobody when earthquake happened.

　　4. as的固定搭配

　　(1) such as

　　举例：

　　I am fond of instruments such as Piano and flute.

　　(2) as to(关于，至于)

　　举例：

　　There is no doubt as to his modest.

　　(3) as soon as

　　举例：

　　I will invite you to my house as soon as i finish all decoration.

　　(4) as long as(只要)

　　举例：

　　As long as you believe me,i will fell happy.