1 用作連詞,表示“當……時候”,引導時間狀語從句,有時表示“一邊……一邊”。
He was reading as she came in. 她進來時他在讀書。
2 用作連詞,表示“因為,既然”,引導原因狀語從句。
As you are busy, let me do it instead. 既然你忙,就讓我做吧。
3 用作連詞,表示“像……一樣,如……一樣”,引導方式狀語從句。
He works as others do. 他像其他人一樣工作。
Do your homework carefully as she does. 像她那樣細心地做作業(yè)。
4 用作介詞,表示“作為”,后跟名詞。
This book is used as a textbook in many schools. 這本書在許多學校被用作課本。
She works as a doctor. 她的職業(yè)是醫(yī)生。