现在完成时用来表示之前已发生或完成的动作或状态，其结果的确和现在有联系。动作或状态发生在过去 但它的影响现在还存在；也可表示持续到现在的动作或状态。其构成： have (has) +过去分词。
（一）表示过去发生或完成的某一动作对现在造成的影响或结果。
如： Have you read that story？
（“读”这一动作发生在过去，对现在造成的影响是：是否知道故事的内容。） 在学习这一概念的同时，还应注意常与现在完成时连用的几个副词：already，just，ever，yet，never等。already，just多用于肯定句中，ever，yet，never多用于疑问句和否定句中。
（二）表示过去已经开始，一直持续到现在的动作或状态。
1、因为表示的是持续的动作或状态，所以使用的动词通常是延续性动词：be, stay, study, wait, keep, have… 等；
2、使用的时间状语通常由for或since 引导，但二者后接的词有所不同：
for后常跟一个时间段，指某个动作到现在为止已持续了多长时间。如：for three years等。
since 作介词，后面可以接一个时间点，如since 1980，也可以接“一段时间+ago”,如: since
three years ago, since two months ago等。since 还可用作连词，引导一个过去时态的时间状语从句。
如：We have known each other since we went to college.
3、非延续性动词不能直接和for 或since 连用，但我们可以找一个相应的延续性动词或动词短语来替换这些非延续性动词，
如: come→be, come to→be in / at, go out→ be out, leave→be away,
begin→be on, stop→ be over， buy→ have, borrow→ keep, open→be open, close→be closed, join→be a member of, die→be dead, catch a cold→have a cold, get to know→know,
become a teacher →be a teacher, fall asleep→be asleep, fall ill→ be ill等。
4、句型It is the first （second, third...) time that...的that从句中，谓语动词须用现在完成时，表示到说话时为止动作发生过几次。如：It is the first time that I have been here.
（三）现在完成时与一般过去时的用法比较
1、 一般过去时表示过去某个时间发生的事、存在的状态或经常发生的动作。说话的侧重点只在于陈述一件过去的事情，不强调对\"现在\"产生的影响。如： He visited Guilin in 1998.
2、 现在完成时表示动作发生在过去，对现在造成了影响或产生了结果。不与确定的过去时间状语连用。如： Jill has bought a new computer. 3、 两种时态的区分
(1)一般过去时的谓语动词用过去式，而现在完成时的谓语基本构成是\"助动词have /has +过去分词\"。
(2)一般过去时通常与表示过去的时间状语连用。如：yesterday, last week, two years ago, just now, in 2002等；
而现在完成时则常与just, already, ever, never等副词和these days, this week, since..., for...等表示一段时间的状语连用。
（3）看看以下的几组句子，有什么区别？
① Have you seen the film?(A) Did you see the film?(B)
[说明] 你看过这部电影吗？(A)句强调的是被问者对剧情是否了解；(B)句强调的是看这部电影的动作是否发生过，并不强调是否知道其内容。 ② How has he done it?(A) How did he do it?(B)
[说明]他是怎么做的这件事？(A)句强调的是他做这件事的方式对现在产生了某种影响；(B)句单纯的询问做这件事的方式。
③ He has lived in Beijing for 8 years.(A) He lived in Beijing for 8 years.(B)
[说明]他在北京住了8年。(A)句讲的是到目前为止他在北京住了8年，可能还会继续在北京住下去。(B)句讲的是他在北京住过8年，现在不在北京了。
动词变化规则
规则动词的过去分词和它的过去式相同,即在原形后加－ed（－d）。已学近80个不规则动词的过去分词约有半数也和它的过去式相同,分类如下,利于记忆: 1) 原形中的元音字母有变化:
get-got-got, sit –sat-sat win-won-won spit- spat- spat shine –shone- shone find- found- found hold-held-held meet- met-met stand- stood-stood understand-understood-understood feed- fed-fed hang-hung-hung 2) 原形中的辅音字母有变化:
make-made-made spill-spilt-spilt have/ has-had-had build-built-built send-sent-sent lend- lent- lent spend-spent-spent 3) 在原形后加t或d:
spoil-spoilt-spoilt learn-learnt-learnt mean-meant-meant hear-heard-heard pay-paid-paid say-said-said lose-lost-lost lay-laid-laid 4) 原形中的元音字母和辅音字母都有变化:
feel-felt-felt smell-smelt-smelt spell-spelt –spelt keep-kept-kept sleep-slept-slept sweep-swept-swept leave-left-left sell-sold-sold
tell-told-told catch-caught-caught teach-taught-taught buy-bought-bought bring-brought-brought think-thought-thought wear-wore-worn 5) 与原形相同:
hit-hit-hit hurt-hurt-hurt let-let-let put-put-put read-read-read set-set-set shut-shut shut cost-cost-cost cut-cut-cut
还有些不规则动词的过去分词与过去式不相同,为便于记忆,也分类如下: 1)原形中的元音字母有变化:
ring-rang-rung sing-sang-sung drink-drank-drunk swim-swam-swum begin-began-begun sink-sank-sunk 2) 在原形上加－en:
eat-ate-eaten fall-fell-fallen ride-rode-ridden write-wrote- written be-was/were-been rise-rose-risen forget-forgot-forgotten 3)在原形上加－n:
see-saw-seen give-gave-given drive-drove-driven take-took-taken mistake-mistook-mistaken draw-drew-drawn blow-blew-blown
grow-grew-grown know-knew-known show-showed-shown throw-threw-thrown 4)在过去式上加－n:
steal-stole-stolen break-broken–broken choose-chose-chosen speak-spoke-spoken wake-woke-woken 6) 与原行相同:come-came-come run-ran-run become-became-become 7) 原形、过去式和过去分词都不相同的:
do-did-done go-went-gone fly-flew-flown lie-lay-lain
个别动词有两个过去式和过去分词,一个为规则变化,另一个为不规则变化: learn-learned-learned shined-shined smell – smelled-smelled
learnt-learnt shine shone-shone smelt-smelt
wake -waked-waked spelled-spelled
woke-woken spell -spelt –spelt
现在完成时
一、写出下列动词的过去式、过去分词： climb-________-________ visit-________-________ try-________-________ learn-________-________ do-________-________ write-________-________ know-________-________ read-________-________ hear-________-________ see-________-________ give-________-________
finish-________-________ live-________-________ clean-________-________ be-________-________ go-________-________ catch-________-________ buy-________-________ teach-________-________ eat-________-________ cut-________-________ sleep-________-________
study-________-________ stay-________-________ work-________-________ have-________-________ buy-________-________ find-________-________ learn-________-________ drink-________-________ tell-________-________ put-________-________ draw-________-________
get-________-________ keep-________-________ take-________-________ 二、Fill in the sentences (第一个空格请用have\\has填空)
1. He ______ already _____ (buy) some milk.
2. She ______ ______ (make) cakes for her husband already. 3. I _____ just ______(write) a letter to my mom.
4. Lily and Merry _____ ever ______ (visit) the White House. 5. Tony_____ already ______(find) his bike. 6. They ______ never _____ (be) to Shanghai. 7. Lucy______ ______ (live) in Panyu for 10 years. 8. We _____ _____ (learn) English since 2-year-old. 9. Tom _______already _______ (climb) up into the tree. 10. I ______ ever ______ (read) the book twice.
11. My brother _____ _____ (go) to Beijing since 2 year ago. 12. Everyone ______ _____(buy) this book since 2 weeks ago. 13. We______ already ______ (finish) the English homework. 14. I _____ _____ (have) the watch for 2 years.
15. My class teacher _____ ______ (teach) in our school since 2001. 16. All of us ______ never ______(know) the good news yet.
17. Tom, Jack and I ______ ______ (study) in middle school for about 1 year. 18. Chinese people ______ _______(drink) tea for thousands of years. 19. Everyone ________ not ______(do) the homework yet. 20. She _____ never ______ (hear) of Kelly’s father before. 三、Fill in the sentences (第一个空格请用have\\has填空) 1. _____ ever ______ (visit) Xiangjiang Zoo. 2. _____already_____ (live) in Panyu for 3 years. 3. Miss Li _____ just _____ (stay) here for half an hour. 4. Jim_____ never _____ (play) table tennis before.
5. The farmers ______ already______ (work) on the farm since 6:30 this morning. 6. Joy and Joyce _____ just ______ (clean) the room. 7. Billy_____ never______ (finish) his homework on time. 8. Everyone________ already_____(try) to put out the terrible fire. 9. He _____ already _____(make) a few mistakes in the exam.
10. We _____ just______(learn) something about water in English lessons. 11. The child _____ never______(drink) wine before.
12. Suzy ______ already_____(draw) three pictures since she came into the classroom.
13. We______ ______(know) each other since we moved here. 14. The poor man ______ never_______(eat) cheese cake before.
15. The pupil ______ just ______(do) his homework for 2 hours. 16. Auntie Su ______ ever ______(give) me two useful books. 17. Tony ______ ever ______(see) the film Hero twice. 18. They _____ already ______(build) 25 houses since 2007. 19. The baby____ already_____(sleep) for 4 hours. 20. Mr. Li ____ ever______(tell) us some amazing news. 四、补全句子。（sth./sb. have/has done）
1. Lin _____already _____in Xiangsheng Middle School for one year.林已经在象圣中学学习
一年了。
2. --How long _____ you _____ here? -- _____ 20 years. 你在这里住多久了？有20年了。 3. We _____ ______6 units since the beginning of this term. 从这学期开始以来，我们已经学了6个
单元了。
4. We _____ already _____ the homework. 我们已经完成作业了。
5. They _____ already ______ the classroom up. 他们已经把教室打扫干净了。 6. _____ you _____ your breakfast yet? 你已经吃早餐了吗？
7. _____ you ever _____ to Beijing? --Yes, I have been there before.你曾经去过北京吗?是的，我之
前去过了。
五、总结：现在完成时 1. 基本结构： 2. 基本句型:
肯定：____________________ 否定：____________________ 疑问：____________________ 3. 常用时间状语和介词
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