(1)as是連詞,意思是"當(dāng)……的時(shí)候,一面……一面",(強(qiáng)調(diào)同時(shí),一般連續(xù)時(shí)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(shí),教師進(jìn)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(shí)候"(一般表示動(dòng)作緊接著發(fā)生);
"那時(shí)"(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(shí)天開始下雨了。
(3)while是"當(dāng)……時(shí)候;和……同時(shí)"(強(qiáng)調(diào)同時(shí)發(fā)生,一般連續(xù)時(shí)間較長)例如:While I was watching TV,he was reading.當(dāng)我在看電視的時(shí)候,他正在看書。While there is life,there is hope.有生命就有希望。