[高中]全新語法:時間狀語從句 三、時間從屬連詞的用法
三、時間從屬連詞的用法
1.when
（1）when引導的時間狀語從句中，既可用短暫性動詞也可用延續(xù)性動詞。
I bought the car when I received my first salary.
我是在領第一筆薪水的時候買的車。（短暫性動作）
Don’t get excited when you talk.說話的時候不要激動。（延續(xù)性動作）
（2）when引導時間狀語從句時，要遵循“主將從現(xiàn)”原則。
I shall tell her the good news when she comes.她來時，我將告訴她這個好消息。
When I grow up，I’ll be a nurse and look after patients.
我長大后要當一名護士，照顧病人。
（3）whenever表示過去或現(xiàn)在的習慣動作，意為“每當……的時候”。
We shall go whenever we are free.我們一有空就去。
They were scolded whenever they were late for school.每當他們上學遲到都要挨罵。
2.while
（1）while引導的時間狀語從句中，只能用延續(xù)性動詞。
They arrived while I was sunbathing.當我正在進行日光浴時，他們來了。
While we were talking，he came in.我們正在談話時，他進來了。
（2）while表示“在……過程中”，強調(diào)某一段時間內(nèi)主句與從句的謂語動作同時發(fā)生。
Keep an eye on my little sister while I am away.我不在時，請照看一下我的小妹妹。
While you are young，you must work hard.趁年輕的時候，你要努力工作。
3.as
（1）as引導時間狀語從句時，多強調(diào)主句和從句中的動作或狀態(tài)同時發(fā)生。
As I waited at the stop，I heard a big noise.在車站等車時，我聽到一個很大的聲響。
She rose up as he entered.他進來時，她站了起來。
（2）as意為“隨著……”，表示隨著時間的變化而變化。
We get wiser as we get older.我們隨著年齡的增長而變得越來越聰明。
As the sun rose the frog dispersed.太陽出來霧就消散。
【比較】 日子一天天過去，天氣越變越壞。
①As the day went on，the weather got worse.（as引導時間狀語從句）
②With the day going on，the weather got worse.（with短語作主語）
4.till，until
（1）till和until 一般可以互換，意為“直到……為止”。
They waited till/until I returned.他們一直等到我回來。
I shall work till/until eleven o’clock.我要工作到11點。
（2）短暫性動詞用于“not ...until”句式；延續(xù)性動詞則用肯定式。
She worked until one o’clock in the morning.她一直工作到凌晨一點。（延續(xù)性動詞）
She did not stop working until one o’clock in the morning.
她一直工作到凌晨一點。（短暫性動詞）
（3）“not until ...”置于句首時用倒裝形式。
Not until 1998 did he return to his hometown.直到1998年他才回到家鄉(xiāng)。
Not until Father came back did we begin to have supper last night.
昨晚直到父親回來，我們才開始吃晚飯。
（4）“not ...until”句式的強調(diào)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.直到見到瑪麗我才高興起來。
5.since
（1）since引導的時間狀語從句用一般過去時，主句用現(xiàn)在完成時，意為“自從……以來”。
Since I left school till now，I have written to him twice.
自從我離開學校到現(xiàn)在，我給他寫過兩封信。
Since he went to Shanghai，I have not heard from him.
自從他去了上海以后，我就沒有接到過他的信。
（2）“It is+一段時間+since”句式
It is a long time since he left.自從他離開，已經(jīng)有很長時間了。
It is three years already since he came to study in this university.
自從他到這個大學來學習，已經(jīng)有三年了。
（3）since引導的時間狀語從句中，謂語動詞用短暫性動詞和延續(xù)性動詞意義不同。
Since he began to live here，I have not seen him.
自從他住到這里，我就沒有見過他。（短暫性動詞）
Since he lived here，I have not seen him.
自從他離開這里，我就沒有見過他。（延續(xù)性動詞）
It is two years since I served in the army.自從我復員以來已經(jīng)兩年了。（延續(xù)性動詞）
It is two years since I began to serve in the army.我參軍已經(jīng)兩年了。（短暫性動詞）
6.before
（1）表示“在……之前”
We do want to buy something now before prices go up.
在物價上漲之前我們的確想買點東西。
The train had left before I arrived at the station.在我到達車站之前火車已開走了。
（2）表示“在……之后才……”
It was midnight before he came back.他半夜以后才回來。
The American Civil War lasted four years before the north won in the end.
美國南北戰(zhàn)爭持續(xù)了四年，北方才最終取得勝利。
（3）表示“還未來得及……就……”
Someone called me up，but they hung up before I could answer the phone.
有人給我打電話，可是我還沒來得及接，電話就掛斷了。
He jumped into the water before I could stop him.
我還沒有來得及阻止他，他就跳進了水里。
（4）表示“趁著……”
We can set off early before it gets hot.我們可以趁著天不熱早點出發(fā)。
You’d better write the phrases down before you forget them.
趁著你還沒有忘記，趕緊把這些詞組寫下來.
Please put them away before they are missing.趁著還沒有丟，把它們收好吧。
（5）表示“不知不覺多少時間已經(jīng)過去了”
Time passed quickly and three years went by before he knew it.
時間飛快地流逝，不知不覺中三年已過去了。
Several weeks had gone by before I realized the painting was missing.
幾周過去了，我才意識到這幅畫不見了。
It was ...before 過了（多長時間）才……
It will be ...before 要用（多長時間）才……
It wasn’t ...before 沒過（多長時間）就……
It won’t be ...before 用不了（多長時間）就會……
