As 作为介词 ^{可以表示“作为”、“以…身份”等}

• In this film, he appeared as a policeman.^{他扮演一名警察。}
• As a mechanic, he can’t always keep himself clean. ^{作为一名机械师…}

As 作为连词 ^{可以表示“因为”、“正当…时候”、“以…方式”或“如同…那样”等}

• You must take care of the baby tomorrow as I am going to London.
• As we were talking about him, he knocked at the door.^{（正当…时候）}
• Do as you are told. ^{叫你怎么做就怎么做(按你被告知的那样去做)（以…方式）}
• As I learned, … ^{（如同…那样）}

work as ^{“担任…工作”}

• I work as an engineer. ^{我是一名工程师。}
• He has worked as a diplomat in the U.S., Sudan and Saudi Arabia. ^{他曾做过驻美国...的外交官。}