一日一词：只有两个字母的难词as

★ As的用法

① 介词，可以表示“作为”、“以……身份”等

In this film, he appeared as a policeman.

在这个电影中，他扮演一个警察。

I work as an engineer.

我是一名工程师。

As a mechanic, he can’t always keep himself clean.

作为一个机械师，他不可能让自己总是很干净。

② 连词，可以表示“因为”、“正当……时候”、“以……方式”

You must take care of the baby tomorrow as I am going to London.（because）因为我要去伦敦，你必须明天照顾孩子。

As we were talking about him, he knocked at the door.(at the time when）正当我们正谈论他的时候，他敲门了。

Do as you are told. 叫你怎么做就怎么做(the thing that）

③ 代词。或“如同……那样”等

As we all know, success comes from hard work.（如同……那样）

众所周知，成功源于勤奋。