1 現(xiàn)在完成時(shí)的概念

現(xiàn)在完成時(shí)表示過(guò)去發(fā)生并且已經(jīng)完成的動(dòng)作對(duì)現(xiàn)在造成影響或后果,以及過(guò)去某一時(shí)間開始并一直持續(xù)到現(xiàn)在的動(dòng)作或狀態(tài)。
現(xiàn)在完成時(shí)是由助動(dòng)詞 have(has)+動(dòng)詞的過(guò)去分詞構(gòu)成。
 
2 現(xiàn)在完成時(shí)的用法:

其主要用法有三種:
I 已完成用法。 表示一個(gè)過(guò)去發(fā)生并結(jié)束的動(dòng)作對(duì)現(xiàn)在產(chǎn)生的結(jié)果和影響。這一類情況可以細(xì)致分為下述兩種情況。
1)表示開始于過(guò)去的動(dòng)作剛剛結(jié)束。常和just,now,already,yet,not…yet等連用。

Li Ming has just turned off the light. 李明剛剛把燈關(guān)上。(說(shuō)明現(xiàn)在燈關(guān)上了)

I've finished my homework now. 現(xiàn)在我已經(jīng)做完作業(yè)了。(說(shuō)明可以交作業(yè)或做別的了)
 
2)表示過(guò)去動(dòng)作的結(jié)果,現(xiàn)在仍殘留著。一般不用時(shí)間狀語(yǔ)。

I have lost my pen. 我把筆丟了。 (說(shuō)明過(guò)去某時(shí)丟的,現(xiàn)在我還沒(méi)找到這支筆)

She has become a teacher. 她已經(jīng)當(dāng)了老師。(說(shuō)明她現(xiàn)在仍是老師)

II 未完成用法。表示過(guò)去已經(jīng)開始,持續(xù)到現(xiàn)在,而且還能繼續(xù)下去的動(dòng)作或狀態(tài)。往往和表示一段時(shí)間的狀語(yǔ)連用。如today,this week(month),lately,recently,these days,in the past few days,during the last two weeks. since,since yesterday,since 2 days ago,since 1991,for a longtime,for a month,so far,up to now,till(until) now等。

He has lived here for 30 years. 他住在這兒三十年了。(現(xiàn)在還住在這兒)

They've known each other since childhood. 他們從小彼此相識(shí)。(現(xiàn)在還繼續(xù)往來(lái))

How long have you studied English? 你學(xué)英語(yǔ)多久了?(現(xiàn)在仍在學(xué))

III 經(jīng)驗(yàn)性用法。表示從過(guò)去到現(xiàn)在之間曾經(jīng)經(jīng)歷過(guò)的事情。一般譯為漢語(yǔ)“過(guò)”,常和often,never,ever,once,twice,three times,before,since等連用。

I have been to the Summer Palace twice. 我曾經(jīng)去過(guò)頤和園兩次。

We have visited your school before. 我以前曾去過(guò)你們學(xué)校。
(過(guò)去的經(jīng)歷,但現(xiàn)在依然記得)

3 現(xiàn)在完成時(shí)的時(shí)間狀語(yǔ)

I 現(xiàn)在完成時(shí)屬于現(xiàn)在時(shí)范圍,故不能和過(guò)去的時(shí)間狀語(yǔ)連用。如:yesterday,last Sunday,in1990,three years ago等。但是,在強(qiáng)調(diào)動(dòng)作產(chǎn)生的后果和影響時(shí),可以和一些表示不確定的時(shí)間狀語(yǔ)連用。

a. 用副詞already和yet。already一般用于肯定句中,yet一般用于否定句和 疑問(wèn)句中。如:We have already finished our homework.我們已完成作業(yè)了。

They haven't finished their homework yet.他們還沒(méi)有完成作業(yè)。
 
b. 用ever 和never。多用于否定或疑問(wèn)句中,表示“曾經(jīng)”或“從未“等。 如:

-Have you ever been to the Great Wall?你曾經(jīng)去過(guò)長(zhǎng)城嗎

-I have never been to the Great Wall.我從未去過(guò)長(zhǎng)城。
 
c. 用表示到說(shuō)話為止的過(guò)去時(shí)間狀語(yǔ),如just,before,up to now,the past few years等。例如:I have seen her before,but I can not remember where. 我以前見過(guò)她,但記不起在哪里見過(guò)。

He has been there three times the last few days. 近幾年他去過(guò)那里三次了。
 
d. 用包括“現(xiàn)在”在內(nèi)的時(shí)間狀語(yǔ),如:now,today,this morning(month,year,term)等。例如:-Have you met him today?-No,I haven't. 今天你見過(guò)他嗎?我 沒(méi)有。

How many times have you been there this year? 今年你去過(guò)那里多少次?

II 短暫性動(dòng)詞不能和表一段時(shí)間的時(shí)間狀語(yǔ)連用。如:come, go, arrive, reach, see, hear, close, leave, begin, start, lose, buy, close, fall, join, die, get up等。但如果要保留表一段時(shí)間的時(shí)間狀語(yǔ),必須將動(dòng)詞改為延續(xù)性動(dòng)詞?,F(xiàn)歸納總結(jié)一下由非延續(xù)性動(dòng)詞到延續(xù)性動(dòng)詞的轉(zhuǎn)換,如:

fall asleep (ill) →be asleep (ill) get to know→ know

begin,(start)→ be on open →be open

buy→ have get up→ be up

die→ be dead go out→ be out

come→ be in close→be closed

arrive→be here join→be in, be a +名詞

finish( end )→be over leave, move →be away, be out of

borrow →keep go to school→be a student

catch(a cold)→ have(a cold) begin to study→study

come back→be back put on→wear 或be on
 
如:He has been a soldier for three years.他參軍三年了。

His father has been dead for two years.他父親去世二年了。

The film has been on for ten minutes.電影已開始十分鐘了。

We have studied English for three years. 我們(開始)學(xué)英語(yǔ)已三年了。