一、由when引導(dǎo)的時(shí)間狀語(yǔ)從句，主句用過(guò)去進(jìn)行時(shí)，從句應(yīng)用一般過(guò)去時(shí)；
When the teacher came in, we were talking.
老師進(jìn)來(lái)時(shí)，我們正在談話。

二、when既可表示某一點(diǎn)時(shí)間，也可以表示某一段時(shí)間 。在when引導(dǎo)的時(shí)間狀語(yǔ)從句中，其謂語(yǔ)動(dòng)詞可以是延續(xù)性的，也可以是非延續(xù)性的，可與主句中的謂語(yǔ)動(dòng)詞同時(shí)發(fā)生，也可在其后發(fā)生。例如：
1. I was just reading a book when she came into my room.
她走進(jìn)我房間時(shí)，我正在看書(shū)。
2. When he was a child he was always trying out new ideas.
他小時(shí)候就常常試驗(yàn)一些新的設(shè)想。

三、下面的例子是一般過(guò)去時(shí)和過(guò)去進(jìn)行時(shí)比較典型的搭配，表示一個(gè)動(dòng)作在發(fā)生的過(guò)程中，又有另一個(gè)動(dòng)作發(fā)生，when引導(dǎo)的是一個(gè)時(shí)間狀語(yǔ)從句。請(qǐng)看以下例句：
1. A woman saw it happen when she was walking past.
一位女子經(jīng)過(guò)正好看見(jiàn)這件事發(fā)生
2. Jane hurt her leg when she was swimming She didn’t notice the big rock in the river.
簡(jiǎn)游泳時(shí)傷了腿，她沒(méi)有注意到河里的大石頭。
3. Tom dropped his camera when he was passing the bridge.
湯姆過(guò)橋時(shí)不慎將照相機(jī)掉了下去。

四、在將來(lái)時(shí)從句中，常用when，且從句須用一般時(shí)代替將來(lái)時(shí)。
1.You shall borrow the book when I have finished reading it．
在我讀完這本書(shū)后，你可以借閱。
2.When the manager comes here for a visit next week，Ill talk with him about this．
下周，經(jīng)理來(lái)這參觀時(shí)，我會(huì)和他談?wù)劥耸隆?/p>

五、when用于表示“一……就……”的句型中（指過(guò)去的事情）。
sb．had hardly（＝scarcely） done sth．when．．．＝Hardly ／ Scarcely had sb．done sth．when．．．
1.I had hardly ／scarcely closed my eyes when someone knocked at the door．＝Hardly ／ Scarcely had I closed my eyes when someone knocked at the door．
我剛一閉上眼，就有人在敲門(mén)了。
2.I had hardly ／scarcely entered my room when the telephone rang．＝Hardly ／Scarcely had I entered my room when the telephone rang．
我剛一走進(jìn)房門(mén)，電話就響了。