since+時間點
for+時間段
Since 用來說明動作起始時間,for用來說明動作延續(xù)時間長度.
since的用法主要有兩點：一是表示“自從……以來”,二是表示“既然”之意.但如果只了解詞的含義,而不了解其用法,在使用時就會造成錯誤.例如：I have not heard from him since I lived in Shanghai.
不少人會望文生義,將該句譯為：“自從我住在上海以來,就再也沒有收到他的信了.”而實際上這個句子的譯文并非如此,那么正確的含義是什么呢?
下面談?wù)剆ince作連詞引導(dǎo)時間狀語從句的用法.
一、若since引導(dǎo)的狀語從句的謂語動詞是終止性的過去時,則從句表示的時間是“從動作開始的那一時刻起”.如：
He has studied very hard since he came to our school.自從他來到我們學(xué)校,他學(xué)習就非常努力.
We have been missing them since they left here自從他們離開這里,我們就一直很想念他們.
這是最常見的一種用法,此處不再多述.
二、若since引導(dǎo)的狀語從句的謂語動詞是持續(xù)性動詞或表示狀態(tài)的動詞的過去時時,則從句表示的時間是“從那持續(xù)動作或狀態(tài)結(jié)束時算起”.如：
I haven’t heard any noise since I slept. Sleep 為持續(xù)性動詞,sleep的動作結(jié)束時,即“醒來”時,這句應(yīng)譯為“我醒后還未聽到任何聲音”.
John is now with his parents in New York, it is already three years since he was a teacher約翰現(xiàn)在和父母一起住在紐約,他不當教師已經(jīng)三年了.
本文開始出現(xiàn)的那個句子就可以譯為“自從我離開上海,就再也沒有收到他的信.”這種譯法常被人們誤用,我們不妨再多舉幾個例子看看：
How long is it since you lived in Shanghai?你離開（沒住在）上海多久了?
It is half a month since he was a League member.他退團（不當團員）半個月了.
It’s been quite some time since I was last in London我離開倫敦已很長時間了.
比較：He has written to me frequently since I was ill.自從我病愈以來,他屢次給我寫信.（從句謂語為狀態(tài)動詞）
He has written to me frequently since I fell ill.自從我生病以來,他就屢次給我寫信.（從句謂語為終止性動詞）
三、若since引導(dǎo)的狀語從句的謂語為持續(xù)性動詞的現(xiàn)在完成時,則表示動作和狀態(tài)延續(xù)到現(xiàn)在（說話時刻）,其表示的時間的起點應(yīng)從動作發(fā)生之時算起.如：
I haven’t heard from him since he has lived there.
這里has lived表示動作的持續(xù)性,時間的起點應(yīng)從：“開始居住”時算起.因此此句可理解為“自從他（開始）住在那兒起,我就一直沒收到他的來信”.
Since we have owned a car, we have gone camping every year.自從我們自己有了汽車,我們每年都去野營.
試比較：1. Since I’ve been at this school, we have had three headmasters.自從我到這所學(xué)校,我們已換了三個校長了.
Since I was at this school, they have had three headmasters.自從我離開這所學(xué)校,他們已換了三個校長了.
2.He has never been to see me since I have been ill. 自從我生病以來,他從未來看過我.
He has never been to see me since I was ill. 自從我病愈以來,他從未來看過我.
由此可見,since引導(dǎo)的從句持續(xù)動詞的一般過去時和現(xiàn)在完成時所表示的意思恰好相反.換言之,前者以肯定的語法形式反映著否定的邏輯內(nèi)容,而后者的形式與內(nèi)容是一致的.
至于It is +一段時間+since…的句型與It has been +一段時間+since…意思相同.前者是規(guī)范說法,后者是口語說法.
應(yīng)注意的是,在這種結(jié)構(gòu)中,since引導(dǎo)的從句絕對不能用否定式的謂語動詞來表示否定意義,下面兩句都錯了：
It is a long time since he didn’t study English.
It’s two months since you didn’t come to see me.
正確的說法為：
It’s a long time since he studied English 他好久沒學(xué)英語了.
You haven’t come to see me for two months. 你有兩個月沒來看我了.
一、延續(xù)性動詞和終止性動詞的概念
英語中,動詞按其動作發(fā)生的方式、動作發(fā)生過程的長短,可分為延續(xù)性動詞和終止性動詞.
延續(xù)性動詞表示能夠延續(xù)的動作,這種動作可以延續(xù)下去或產(chǎn)生持久影響.如：learn, work, stand, lie, know, walk, keep, have, wait, watch, sing, read, sleep, live, stay等.
終止性動詞也稱非延續(xù)性動詞、瞬間動詞或短暫性動詞,表示不能延續(xù)的動作,這種動作發(fā)生后立即結(jié)束.如open, close, finish, begin, come, go, arrive, reach, get to, leave, move, borrow,buy等.
二、延續(xù)性動詞的用法特征
1.延續(xù)性動詞可以用于現(xiàn)在完成時,其完成時態(tài)可與表示"段時間"的狀語連用.表示"段時間"的短語有：for two years, during the past three years, since last year, how long等.如：I have learned English since I came here.自從我來到這兒就學(xué)英語了.
2.延續(xù)性動詞不能與表示短暫時間的"點時間"狀語連用.如：It raind at eight yesterday morning.(誤) rain為延續(xù)性動詞,而at eight表示"點時間",前后顯然矛盾.如果用延續(xù)性動詞表示一瞬間的動作,可以借助come, begin, get等終止性動詞來表示.上句可改為：It began to rain at eight yesterday morning.(正)又如：
-When did you get to know Jack?
-Two years ago.
-Then you've known each other for more than two years.
-That's right.
三、終止性動詞的用法特征
1.終止性動詞可用來表示某一動作完成,因此可用于現(xiàn)在完成時.如：
The train has arrived.火車到了.
Have you joined the computer group?你加入電腦小組了嗎?
2.終止性動詞表示的動作極其短暫,不能持續(xù).因此,不可與表示一段時間的狀語連用(只限肯定式).如：
(1)他死了三年了.
誤：He has died for three years.
正：He has been dead for three years.
正：He died three years ago.
正：It is three years since he died.
正：Three years has passed since he died.
(2)他來這兒五天了.
誤：He has come here for five days.
正：He has been here for five days.
正：He came here five days ago.
正：It is five days since he came here.
正：Five days has passed since he came here.
(1)、(2)句中的die、come為終止性動詞,不能與表示"段時間"的狀語連用.那么,應(yīng)如何正確表達呢?可以采用下面的四種方法：
(1)將句中終止性動詞轉(zhuǎn)換為相應(yīng)的延續(xù)性動詞,如上面兩例中的第一種正確表達方式.下面列舉幾例：leave→be away, borrow→keep, buy→have, begin/start→be on, die→be dead, move to→live in, finish→be over, join→be in/be a member of, open sth.→keep sth. open, fall ill→be ill, get up→be up, catch a cold→have a cold.
(2)將句中表示"段時間"的狀語改為表示過去確定時間的狀語,如下面兩例中的第二種正確表達方式.
(3)用句型"It is+段時間+since..."表達原意,如上面兩例中的第三種正確表達方式.
(4)用句型"時間+has passed+since..."表達原意,如上面兩例中的第四種正確表達方式.
3.終止性動詞可用于現(xiàn)在完成時否定式中,成為可以延續(xù)的狀態(tài),因而可與表示一段時間的狀語連用.如：
He hasn't left here since 1986.
I haven't heard from my father for two weeks.
4.終止性動詞的否定式與until/till連用,構(gòu)成"not+終止性動詞+until/till ..."的句型,意為"直到……才……".如：
You can't leave here until I arrive.直到我到了,你才能離開這里.
I will not go to bed until I finish drawing the picture tonight.今天晚上直到我畫完畫,我才上床睡覺.
5.終止性動詞可以用于when引導(dǎo)的時間狀語從句中,但不可以用于while引導(dǎo)的時間狀語從句中.when表示的時間是"點時間"(從句謂語動詞用終止性動詞),也可以是"段時間"(從句謂語動詞用延續(xù)性動詞).而while表示的是一個較長的時間或過程,從句謂語動詞用延續(xù)性動詞.如：
When we reached London, it was twelve o'clock. (reach為終止性動詞)
Please look after my daughter while/when we are away. (be away為延續(xù)性動詞短語)
6.終止性動詞完成時不可與how long連用(只限于肯定式).如：
誤：How long have you come here?
正：How long have you been here?
正：When did you come here?