[高中]全新语法:时间状语从句 三、时间从属连词的用法
三、时间从属连词的用法
1.when
（1）when引导的时间状语从句中，既可用短暂性动词也可用延续性动词。
I bought the car when I received my first salary.
我是在领第一笔薪水的时候买的车。（短暂性动作）
Don’t get excited when you talk.说话的时候不要激动。（延续性动作）
（2）when引导时间状语从句时，要遵循“主将从现”原则。
I shall tell her the good news when she comes.她来时，我将告诉她这个好消息。
When I grow up，I’ll be a nurse and look after patients.
我长大后要当一名护士，照顾病人。
（3）whenever表示过去或现在的习惯动作，意为“每当……的时候”。
We shall go whenever we are free.我们一有空就去。
They were scolded whenever they were late for school.每当他们上学迟到都要挨骂。
2.while
（1）while引导的时间状语从句中，只能用延续性动词。
They arrived while I was sunbathing.当我正在进行日光浴时，他们来了。
While we were talking，he came in.我们正在谈话时，他进来了。
（2）while表示“在……过程中”，强调某一段时间内主句与从句的谓语动作同时发生。
Keep an eye on my little sister while I am away.我不在时，请照看一下我的小妹妹。
While you are young，you must work hard.趁年轻的时候，你要努力工作。
3.as
（1）as引导时间状语从句时，多强调主句和从句中的动作或状态同时发生。
As I waited at the stop，I heard a big noise.在车站等车时，我听到一个很大的声响。
She rose up as he entered.他进来时，她站了起来。
（2）as意为“随着……”，表示随着时间的变化而变化。
We get wiser as we get older.我们随着年龄的增长而变得越来越聪明。
As the sun rose the frog dispersed.太阳出来雾就消散。
【比较】 日子一天天过去，天气越变越坏。
①As the day went on，the weather got worse.（as引导时间状语从句）
②With the day going on，the weather got worse.（with短语作主语）
4.till，until
（1）till和until 一般可以互换，意为“直到……为止”。
They waited till/until I returned.他们一直等到我回来。
I shall work till/until eleven o’clock.我要工作到11点。
（2）短暂性动词用于“not ...until”句式；延续性动词则用肯定式。
She worked until one o’clock in the morning.她一直工作到凌晨一点。（延续性动词）
She did not stop working until one o’clock in the morning.
她一直工作到凌晨一点。（短暂性动词）
（3）“not until ...”置于句首时用倒装形式。
Not until 1998 did he return to his hometown.直到1998年他才回到家乡。
Not until Father came back did we begin to have supper last night.
昨晚直到父亲回来，我们才开始吃晚饭。
（4）“not ...until”句式的强调形式。
It was not until yesterday that I noticed it.直到昨天我才注意到此事。
It was not until I saw Mary that I felt happy.直到见到玛丽我才高兴起来。
5.since
（1）since引导的时间状语从句用一般过去时，主句用现在完成时，意为“自从……以来”。
Since I left school till now，I have written to him twice.
自从我离开学校到现在，我给他写过两封信。
Since he went to Shanghai，I have not heard from him.
自从他去了上海以后，我就没有接到过他的信。
（2）“It is+一段时间+since”句式
It is a long time since he left.自从他离开，已经有很长时间了。
It is three years already since he came to study in this university.
自从他到这个大学来学习，已经有三年了。
（3）since引导的时间状语从句中，谓语动词用短暂性动词和延续性动词意义不同。
Since he began to live here，I have not seen him.
自从他住到这里，我就没有见过他。（短暂性动词）
Since he lived here，I have not seen him.
自从他离开这里，我就没有见过他。（延续性动词）
It is two years since I served in the army.自从我复员以来已经两年了。（延续性动词）
It is two years since I began to serve in the army.我参军已经两年了。（短暂性动词）
6.before
（1）表示“在……之前”
We do want to buy something now before prices go up.
在物价上涨之前我们的确想买点东西。
The train had left before I arrived at the station.在我到达车站之前火车已开走了。
（2）表示“在……之后才……”
It was midnight before he came back.他半夜以后才回来。
The American Civil War lasted four years before the north won in the end.
美国南北战争持续了四年，北方才最终取得胜利。
（3）表示“还未来得及……就……”
Someone called me up，but they hung up before I could answer the phone.
有人给我打电话，可是我还没来得及接，电话就挂断了。
He jumped into the water before I could stop him.
我还没有来得及阻止他，他就跳进了水里。
（4）表示“趁着……”
We can set off early before it gets hot.我们可以趁着天不热早点出发。
You’d better write the phrases down before you forget them.
趁着你还没有忘记，赶紧把这些词组写下来.
Please put them away before they are missing.趁着还没有丢，把它们收好吧。
（5）表示“不知不觉多少时间已经过去了”
Time passed quickly and three years went by before he knew it.
时间飞快地流逝，不知不觉中三年已过去了。
Several weeks had gone by before I realized the painting was missing.
几周过去了，我才意识到这幅画不见了。
It was ...before 过了（多长时间）才……
It will be ...before 要用（多长时间）才……
It wasn’t ...before 没过（多长时间）就……
It won’t be ...before 用不了（多长时间）就会……
