when的用法有哪些

2019-09-29 16:04:38
when的用法有哪些

when可以用作副词、连词和代词,其中副词可用作疑问副词、连接副词和关系副词等;连词可用作从属连词和并列连词等;用作代词位于介词之后。

1when用作副词

用作疑问副词,引导特殊疑问句.例如:

When will you come to see me?你什么时候要来看我?

When are they going to visit the Great Wall?他们打算什么时候去游览长城?

用作连接副词,通常用来引导主语从句、表语从句、同位语从句、宾语从句及起名词作用的“ when +动词不定式”结构.例如:

When he comes is not known.他何时来还不知道.

The morning is when I am busiest.早上是我最忙的时候.

I have no idea when the game will begin.我不知道比赛何时开始.

I dont know when the plane takes off.我不知道飞机何时起飞.

I dont know when to leave for London.我不知道该在何时动身去伦敦.

用作关系副词,引导限定性定语从句和非限定性定语从句.例如:

Do you still remember the days when we stayed in America?你还记得我们呆在美国的那些日子吗?

The day will come soon when the Chinese astronauts will go to the moon.中国宇航员登上月球的那一天很快就要到来了.

It happened ten years ago,when I was a child.事情发生在十年前,当时我还是个小孩子.

We will go to the countryside at the beginning of June,when the summer harvest will start.我们将在六月初下乡,那时夏收就要开始了.

1when用作连词

用作从属连词,意为“当……的时候”,引导时间状语从句.例如:

They learned a lot from the peasants when they stayed in the village.

他们住在那个村子时,从农民那里学到了许多东西.

It was snowing when he arrived at the station.他到达车站时,天正下着雪.

注意:如果 when 引导的从句中的主语和主句中的主语一致,且从句中的谓语动词是“ be +分词”或从句主语是 it ,则 be 动词及其主语常可省略.例如:

When( he was ) asked why he was late,he made no answer.当被问到他为什么迟到时,他避而不答.

Ill tell him about it when ( it is ) possible.在可能的时候,我会把那件事告诉他的.

用作从属连词,意为“一……就……”,引导时间状语从句.例如:

We will stand up when the teacher comes into the classroom.老师一进教室我们就起立.

Fire the rockets when I give the signal.我一发信号,你就点燃火箭.

用作从属连词,意为“还没 / 刚刚……就”,引导时间状语从句.例如:

I had hardly opened the door when he came in.我刚一开门,他就进来了.

I had not been reading for half an hour when I heard someone call my name.我刚刚看了半个小时的书,就听到有人叫我的名字.

用作从属连词,意为“倘若,如果”,表示条件.例如:

He will be likely to recover when he is operated on.如果动手术,他有可能康复.

Turn off the switch when anything goes wrong with the machine.如果机器发生故障,就把电源关上.

用作从属连词,意为“既然,尽管”,表示让步.例如:

Why use metal when you can use plastic?既然能用塑料,为什么用金属呢?

They kept trying when they knew it was hopeless.尽管他们知道那件事没有希望,可是他们还在不断地努力.

用作并列连词,意为“在那时,届时”,表示时间.这时主句中可以用过去进行时,过去完成时或“ was/were about to do sth.”结构.例如:

Last night I was about to go to bed when the phone rang.昨天晚上我正要上床睡觉时,电话铃响了.

I was cooking in the kitchen when someone knocked at the door.我正在厨房做饭,这时有人敲门.

He had just finished the book when supper was served.我刚刚读完这本书,这时晚饭就端上来了.

用作并列连词,意为“虽然、然而、可是”,表示转折.例如:

He usually walks to work when he might take a bus.虽然他可以坐公共汽车上班,但他却常常步行上班.

I had only twenty dollars when I needed thirty to buy the dictionary.

我需要30买那本字典,可是我只有20.

用作并列连词,意为“而、却”,表示对比.例如:

How can he say that everything is fine when its obvious that it is not?他怎能说一切都好呢?情况显然不是那样.

1when用作代词

when作为代词常常位于介词之后,意为“那时,什么时候”.例如:

We came back on Tuesday,since when we have been working in the repair shop.我们星期二回来,从那时起就一直在修配车间工作.

Since when have you been studying Japanese?你是从何时起一直学习日语的?

另外,when 还可用作名词,前面常常用定冠词 the .the when 表示事件发生的时间,常常与 the where,the how 并列使用.例如:

He told the police the when and the how of the accident.他告诉警察事故发生的时间及发生的原委.

(责任编辑:三剑客)