(1)as 是連詞,意思是"當(dāng)……的時候,一面……一面",(強調(diào)同時,一般連續(xù)時間不長),如:
As we were talking about Titanic, our teacher came in. 正當(dāng)我們談?wù)?泰坦尼克號"這部電影時,教師進來了。
The students sing as they go along. 學(xué)生們邊走邊唱。
(2)When和as一樣都是連詞,注意它們的不同。如when"當(dāng)……的時候"(一般表示動作緊接著發(fā)生);
"那時"(等立連詞,前有逗號分開)I stayed till sunset, when it began to rain. 我一直呆到太陽下山,那時天開始下雨了。
(3)while是"當(dāng)……時候;和……同時"(強調(diào)同時發(fā)生,一般連續(xù)時間較長)例如:While I was watching TV, he was reading. 當(dāng)我在看電視的時候,他正在看書。While there is life, there is hope. 有生命就有希望。