初中·課本中不會(huì)教你的 243　when, while, as和as soon as

243　when, while, as和as soon as

1　when, while和as 都可以引導(dǎo)狀語(yǔ)從句，表示在一個(gè)時(shí)間段內(nèi)某個(gè)動(dòng)作正在發(fā)生，從句中用進(jìn)行時(shí)態(tài)。

When I was walking along the road, I saw some children playing on the grass. 我沿著馬路向前走時(shí)，看見(jiàn)一些兒童在草地上玩。

Mother came in while she was crying. 她正在哭時(shí)，母親進(jìn)來(lái)了。

As I was sitting under a tree, I found a bag. 我坐在一棵樹(shù)下時(shí)，發(fā)現(xiàn)了一只包。

2　when 既可以表示一個(gè)時(shí)間段，也可以表示一個(gè)時(shí)間點(diǎn)（一瞬間）；表示一個(gè)時(shí)間段時(shí)，從句謂語(yǔ)動(dòng)詞用進(jìn)行時(shí)態(tài)，表示一個(gè)時(shí)間點(diǎn)時(shí)，從句謂語(yǔ)動(dòng)詞根據(jù)具體情況用一般過(guò)去時(shí)或一般現(xiàn)在時(shí)。when 引導(dǎo)的時(shí)間狀語(yǔ)從句里的謂語(yǔ)動(dòng)詞，既可以是延續(xù)性的，也可以是非延續(xù)性的。

When/While/As I was having supper , someone knocked at the door. 我在吃晚飯時(shí)，有人敲門(mén)。（was having supper表示一個(gè)時(shí)間段 ）

It was twelve o'clock when she went to bed . 她是12點(diǎn)鐘上床的。（went to bed表示一個(gè)時(shí)間點(diǎn) ）

提示

when作疑問(wèn)副詞用時(shí)，表示一個(gè)時(shí)間點(diǎn)，句中謂語(yǔ)動(dòng)詞要用一般過(guò)去時(shí)，不可用現(xiàn)在完成時(shí)。

When did you come？（正）你什么時(shí)候來(lái)的？

When have you come? （誤）

3　while 表示一個(gè)時(shí)間段，引導(dǎo)的從句常用進(jìn)行時(shí)態(tài)，表示一個(gè)動(dòng)作正在進(jìn)行時(shí)，另外發(fā)生了什么事。要表示兩個(gè)動(dòng)作同時(shí)進(jìn)行或兩種情況對(duì)比時(shí)，常用while 。

He came in while I was reading the newspaper. 我正在讀報(bào)時(shí)他進(jìn)來(lái)了。

She was watering the flowers while I was working. 我在工作時(shí)，她在澆花。（主句和從句都用進(jìn)行時(shí)態(tài) ）

What were you doing while he was watching TV？他看電視時(shí)你在干什么？

Strike while the iron is hot. 趁熱打鐵。

He fell asleep while listening. 他聽(tīng)著聽(tīng)著睡著了。

提示

①while不能表示一個(gè)時(shí)間點(diǎn)。

你離開(kāi)房間時(shí)，請(qǐng)把燈關(guān)掉。

When you leave the room, please turn off the lights. （正）

While you leave the room, please turn off the lights. （誤）

②while可用作名詞，意為“一會(huì)兒，一段時(shí)間”，常同a連用。

After a while they went home. 過(guò)了一會(huì)兒，他們回家了。

Please wait for a while . 請(qǐng)等一會(huì)兒。

4　as 表示兩個(gè)短促行為、事件同時(shí)發(fā)生或交替進(jìn)行，有時(shí)表示“一邊……一邊……”。

As/When I opened the window, I saw the sun rising. 我打開(kāi)窗時(shí)，看見(jiàn)太陽(yáng)正在升起。

He looked behind as he ran. 他一邊跑一邊朝后看。

She sings as she dances. 她一邊跳一邊唱。（不可用when, while ）

I saw her as she was getting off the bus.她下公共汽車(chē)時(shí)我看見(jiàn)了她。

5　as soon as 意為“一……就”，引導(dǎo)時(shí)間狀語(yǔ)從句。注意，as soon as 所引導(dǎo)的從句要用一般現(xiàn)在時(shí)代替一般將來(lái)時(shí)，而其主句常用一般將來(lái)時(shí)。

We'll go home as soon as the rain stops. 雨一停我們就回家去。

I'll tell her the news as soon as I see her. 我一看到她就告訴她這個(gè)計(jì)劃。