介詞before 與 after 的用法
　　before”與“after”?
　　2008-01-16 18:16:28
　　用漢語表達時間的先后時,人們通常用“以前”和“以后”,詞的變化不大,而且重復率非常高.受此影響,不少學生在英語里也千篇一律地用“before”和“after”來表達這兩層意思.其實在英語詞匯里可以表達這兩層意思的詞有很多個,其中有幾個使用頻率特別高,但它們在用法上有差異,極易混用.掌握這些詞的用法,正確區(qū)分它們的差異,可以幫助我們寫作時避免用詞重復,結(jié)構(gòu)單調(diào),使文章生動.由于這些詞屬于高頻詞,把握好這些詞,對準確理解和翻譯也不無幫助.下面就對相關詞進行歸納和比較.
　　一、表達“在……之前”的詞
　　1. before prep. , adv. conj.
　　(a)To my knowledge it has never been done before.
　　據(jù)我所知,以前從未有人這樣做過.
　　(b)My father died before I was born.
　　我父親在我出生之前就去世了.
　　(c)Before being supplied to houses, the water must be treated to make it suitable for drinking.
　　水在供給各用戶之前應加以處理使之適于飲用.
　　2. until prep. , conj.
　　(a)Until the twentieth century man used water, wood and fossil fuels as sources of power.
　　在20世紀以前,人們使用水、木柴和礦物燃料來作能源.
　　(b)Until penicillin was developed, man could do little with the disease.
　　在研制出青霉素之前,人類對這種病毒幾乎無能為力.
　　(c)Color was a mystery until the time of Newton.
　　在牛頓時代以前,顏色是個神秘的東西.
　　〔注〕：before與until當連詞用時,都表示主句的情景發(fā)生在從句情景之前,它們主要有兩個區(qū)別：
　　第一,帶有until從句的肯定式主句中的謂語動詞必須是持續(xù)性的（如be, live, like, work等）,而帶before從句的主句中的謂語動詞則不必是持續(xù)性的.比較：
　　(a)We always have to wait until the last passenger has left.
　　我們總是得等到最后一個乘客離去.
　　(b)I shouted before the boss arrived.
　　在老板到來之前,我大喊大叫.
　　第二,until引出的分句的內(nèi)容是真實的,而before引出的分句的內(nèi)容可能是真實的,也可能是非真實的.比較：
　　(a)Let's wait until the rain stops.
　　讓我們等到雨停吧.
　　(b)I began to cry before he could speak.
　　他尚未開口,我就開始哭了.
　　(c)Pigs will fly before he'll become a mathematician.
　　他要是能當數(shù)學家,豬都會飛了（在他成為數(shù)學家之前豬都會飛了.意即根本不可能）.
　　3. Previous a. ,adv.
　　(a)With the help of his coach, he has recovered to the previous level.
　　在教練的幫助下,他已經(jīng)恢復到以前的水平.
　　〔注〕：previous當副詞用常與to連用
　　(b)You are expected to make full investigations previous to reaching a conclusion.
　　希望你們下結(jié)論之前先作先分調(diào)查.
　　(c)Previously, the local people used wood and coal to provide power and heating.
　　以前,當?shù)厝擞媚静窈兔簛硖峁﹦恿腿剂?
　　4. prior (to) a. ,adv.
　　(a)It happened prior to the warning of the government.
　　這發(fā)生在政府發(fā)出警告以前.
　　(b)The contract will be signed prior to the ceremony.
　　合同將在儀式之前簽署.
　　(c)It is believed that the skill was developed prior to Ming Dynasty.
　　人們相信這項技術在明朝以前就已經(jīng)發(fā)明了.
　　〔注〕：prior to和before雖然可以通用,但有人認為prior to最好避免用在句首.
　　二、表達“在……之后”的詞
　　1. after prep. , adv. conj.
　　(a)After testing, the engine was put into immediate service.
　　經(jīng)過試驗以后,發(fā)動機立即交付使用.
　　(b)It happened twenty years after.
　　這事發(fā)生在20年之后.
　　(c)After one cycle is completed, another cycle begins.
　　一個循環(huán)完成后,另一個循環(huán)又開始.
　　2.in prep.
　　(a)In about five years, what I have said today will become true.
　　大約5年以后,我今天所說的就會變成現(xiàn)實.
　　(b)In the four years that followed, I studied in the Department of Accounting.
　　在以后的4年中,我在會計系學習.
　　(C)It's two o’ clock. I'll come in an hour.
　　現(xiàn)在是兩點,我一小時后到.
　　〔注〕：在表示以現(xiàn)在為起點的“在……之后”這個含義時,介詞in之后應接時間段(a period of time),介詞after之后則應該接時間點(a point of time).比較：
　　(a)I've ordered a taxi. It will arrive here in 10 minutes.
　　我已經(jīng)叫了出租車,10分鐘以后就會到.
　　(b)He will graduate in four years.
　　他4年以后畢業(yè).
　　(c)He will be back after three o'clock.
　　他3點以后到.
　　但是,當以某個過去的時間為起點時,after之后既可以接時間點,也可以接時間段.比如：
　　(a)Just after six the meeting was over.
　　剛過6點,會議就結(jié)束了.
　　(b)After half month of war Japan was badly defeated.
　　經(jīng)過半個月的戰(zhàn)爭,日本被打得慘敗.
　　(c)After seven days of this I went to a party.
　　這樣過了7天以后,我去參加一個聚會.
　　3. later
　　(a)Fuller report will be published at a later date.
　　更詳細的報告會在以后出版.
　　(b)I don't know what would happen later on.
　　至于以后怎么樣,我就不知道了.
　　(c)He handed in his resignation, and later (on)regretted his hasty action.
　　他交了辭職書以后,又為自己的草率感到后悔.
　　〔注〕：later還可譯為“過一會兒”,“過了一會兒”,“后來”等.
　　4.afterward(s) adv.
　　(a)She had her supper and went bed soon afterwards.
　　她吃過晚飯之后不久就去睡覺了.
　　(b)I didn't see him afterwards.
　　以后我再也沒有見到他了.
　　(c)I was a bit rude to her at the meeting, and afterwards I apologized.
　　在會上我對她是有點粗暴,但是（散會）以后我向她道了歉.