1.引導(dǎo)時(shí)間狀語從句的引導(dǎo)詞有：
�、俦硎灸硞�(gè)時(shí)刻發(fā)生的動(dòng)作：when、while、as、once
�、诒硎灸硞�(gè)時(shí)刻之前發(fā)生的動(dòng)作：before、until
�、郾硎灸硞�(gè)時(shí)刻之后發(fā)生的動(dòng)作：after、since
2. when引導(dǎo)從句時(shí)，主從句的動(dòng)作有先有后，也可以同時(shí)進(jìn)行,從句的動(dòng)作可以是持續(xù)性的，也可以是短暫的。
eg. When I go to the cinema, the movie had already started. （主先從后）（短暫性）
When I watched movie, I used to eat ice cream. (同時(shí)) （持續(xù)性）
When the movie ended, the people went back. （從先主后）
3. while側(cè)重主從句動(dòng)作的`對(duì)比，且從句的動(dòng)詞必須是持續(xù)性的。
eg. While we were chatting she was reading comic．
4. as引導(dǎo)從句時(shí)側(cè)重主從句動(dòng)作同時(shí)或幾乎同時(shí)進(jìn)行，從句的動(dòng)作可以是持續(xù)性的，也可以是短暫的。
eg. Sometimes I watch TV as I am having breakfast．
5. 關(guān)于when的固定搭配：
�、佟瓀as/were doing…when…（正在做…突然）
�、凇瓀as/were about to do…when…（剛要做…突然）
�、邸瓀as/were on the point of doing…when…(剛要做…突然)
④…h(huán)ad just done…when….(剛一…就)
�、軭ardly/Scarcely had…done…when…(剛一…就)