when的用法

華冰

when是歷年各地高考英語試卷考查得較為頻繁的一個詞，其用法是多種多樣的，下面就對其用法作簡單的小結(jié)，并輔之以例句。

1. 作疑問副詞，引導(dǎo)特殊問句，意思是“什么時候，何時”。

When will he leave？

2. 作連接副詞，引導(dǎo)名詞性從句或不定式短語，意思是“什么時候”。如：

I remember when this used to be a quiet village.

Id like to know when they will come.

When we shall have our English evening party is still a question.

Have you decided when to go sightseeing？

3. 作疑問代詞，常與介詞since， till， up to等連用，意思是“……時候”。如：

Since when/what time have they had the house？

Till when is the library open？

They left on Monday， since when （=since Monday） we have heard nothing.

4. 作關(guān)系副詞，引導(dǎo)限定性定語從句和非限定性定語從句。如：

The day when/on which they were to leave finally arrived.

At the time when I saw him， he was well.

上面兩句中的when均可換用that。

The film brought the hours back to me when I was take good care of in that faraway village.

Sunday is a holiday， when people do not go to work.

I will see you in October， when I come back.

5. 在某些含有“時間”的名詞詞組后面，由于該名詞不表示時間，或整個名詞詞組已用作連詞，不宜用when來引導(dǎo)。如：

This is the first time （that） I have read an English novel in the original.

Each time he came， he would bring us some good news.

I called on him the day I returned home.

6. 作從屬連詞，引導(dǎo)狀語從句，表示多種語法意義。

（1）表示時間，有“當……時，在……的時候”的含義，此時when后面的從句是用來說明前面主句動作發(fā)生的背景。如：

Dont be afraid of asking for help when it is needed.

James pretended to be deaf when I spoke to him.

（2）表示條件，意思上接近“在……的情況下”，相當于if，有“如果，要是”的含義。如：

Come when you are ready.

Please turn off the switch when anything goes wrong with the machine.

（3）表示對比，相當于whereas， while，有“雖然，可是，而”的意思。如：

He usually walks when he might ride.

Why are you here when you should be in school？

（4）表示時間，相當于as soon as，有“一……就”的意思。如：

We will start when the team leader comes.

（5）相當于considering that， although， as，有“既然，考慮到，雖然”的意思，從句說明主句的理由。如：

I cant tell you anything when you wont listen.

Why do you want a new job when youve got such a good one already？

（6）表示某事突然發(fā)生，相當于and just at that time， and then，有“正在這時，這時突然”的意思。如：

I was getting up when the doorbell rang.

She was about to leave the office when it began to rain.

（7）表示“剛剛……就，還沒……就”的含義，表示主、從句的動作幾乎同時發(fā)生。主句常為過去完成時，并與just， hardly等連用，從句為過去時。如：

I had hardly opened the door when he hit me.

I had hardly/barely/scarcely finished writing my letter when I heard a knock at the door.

（8）有“正……忽然……”的含義，表示突然發(fā)生某事。when之前的主句說明when之后的從句動作發(fā)生的背景。如：

I was about to leave my office when the telephone rang.

在這種句型中，一般不能將when放在句首。

（9）有“無論什么時候……”的含義，與whenever的意思差不多，但語氣較輕。此時when后的從句說明主句動詞動作發(fā)生的背景。如：

When the wind blows， all the doors rattle.

（10）有“本該（可）……而（卻）……”的含義，此時when含有對比意義。如：

They have only three copies when we need five.

（11）有“那時”或“然后”的含義，此時when前往往有逗號。例如：

They arrive at 6， when we all have dinner.

（12）有“其實或雖然……但是……”的含義，此時when的意思接近although。如：

She stopped trying， when she might succeed next time.

（13）when引導(dǎo)狀語從句時，在不影響文章意思情況下往往將從句的某些成分省去，因此常常會出現(xiàn)以下結(jié)構(gòu)。

①when+現(xiàn)在分詞。如：

when sleeping， I never hear a thing.

②when+過去分詞。如：

This dictionary will look nice when printed.

③when+名詞或形容詞。如：

When a boy， he was sick all the time.

④when+介詞短語。如：

When at Rome do as Romans do.

7. 由when等引導(dǎo)的狀語從句，如果其主語與主句的主語一致或是it，謂語動詞又含有be時，主語和be常常被省去，只保留連詞、表語或分詞（短語）。如：

When （I was） a boy， I went to swim in the lake every summer.

When （we are） young， we are full of hope and anxieties.

Metals expand when heated and contract when cooled.

8. 在表示同時，即“在……的時候”時，?？膳cwhile， as互換使用。如：

When/While/As I was taking a wilk in the park， I saw two men fighting.

9. 有時可以代替whenever，意思是“任何時候”。如：

Come when（ever） you please.

You may begin when（ever） you are ready.

10. when也可作名詞，意思是“時間”。如：

Please tell me the when and（the） how of it.

He asked them the when and（the） where of the traffic accident.