一. 现在完成时的构成:主语+have(has)+过去分词
过去分词的构成：规则动词的过去分词的构成：四种情况：
（一）1．一般的也是绝大多数的动词是直接在后面加-ed，例如，played
2．以e结尾的动词只加-d，例如，loved
3．以辅音字母+y结尾的，变y为i再加-ed 例如, worried
4．以一个辅音字母（r/w/y除外）结尾的重读闭音节，要双写这个辅音字母再加ed，例如，stopped, planned,
（二）不规则动词的变化规则：这些不规则动词有下面一些规律可循，
1. AAA型：let, set. hit .cut. put, shut .cost. hurt, read. spread
2. AAB型：只有一个，beat---beat---beaten
3. ABA型：run. come, become. overcome（克服）
4．ABB型：可分为下面六组：
第一组：都以t结尾. feel. keep. sleep weep sweep meet leave smell. deal spoil spill
第二组：都是变d为t spend lend send build
第三组：都是变其中的元音字母 lose get win shine dig hang
第四组：都以ught结尾, 其中catch, teach以aught结尾 bring buy fight think catch teach
第五组：都以“d”结尾 tell sell lay pay say
第六组：无规律组，必须硬记. find stand understand sit have make hold hear mean
5.ABC型: 第一组：在过去式上加 -n （注：过去式都是以“o＋辅音字母+e”结尾的，但rise除外）
break-broke-broken choose-chose-chosen forget-forgot-forgotten freeze-froze-frozen
steal-stole-stolen
第二组 :在原形上加-n
see-saw-seen give-gave-given drive-drove-driven
take-took-taken draw-drew-drawn grow-grew-grown
know-knew-known throw-threw-thrown blow-blew-blown
show-showed-shown mistake-mistook-mistaken rise-rose-risen
第三组：在原形上加 -en
write-wrote-written(双写t) eat-ate-eaten fall-fell-fallen
ride-rode-ridden
be-was/were-been
第四组：符合 i-a-u的原则，并且发音规律相同。
begin-began-begun
sing-sang-sung
swim-swam-swum sink-sank-sunk(沉 ) drink-drank-drunk 第五组：bear-bore-born wear-wore-worn tear-tore-torn 第六组：lie-lay-lain do-did-done go-went-gone fly-flew-flown ring-rang-rung (双写d) hide-hid-hidden(双写d) wake-woke-woken speak-spoke-spoken
二.现在完成时的用法:
I.“已完成”用法 :表示一个过去发生并结束的动作对现在造成的影响或结果。
1）表示开始于过去的动作刚刚结束。常和just，now，already，yet，not…yet等不确定的时间状语连用。
Li Ming has just turned off the light. 李明刚刚把灯关上。（说明现在灯关上了）
I've finished my homework now. 现在我已经做完作业了。（说明可以交作业或做别的了） 2）表示过去动作的结果，现在仍残留着。一般不用时间状语。
I have lost my pen. 我把笔丢了。 （说明过去某时丢的，现在我还没找到这支笔） She has become a teacher. 她已经当了老师。（说明她现在仍是老师）
II.“未完成”用法。表示动作或状态从过去某时开始，持续到现在，可能继续下去，也可能刚刚结束。常和表示一段时间的状语连用。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 long time，for a month，so far，up to now，till（until） now等。
He has lived here for 30 years. 他住在这儿三十年了。（现在还住在这儿）
They've known each other since childhood. 他们从小彼此相识。（现在还在往来） How long have you studied English？ 你学英语多久了？（现在仍在学）
III.经验性用法:表示从过去开始到目前为止这段时间中反复发生的动作或多次出现的状态。常与频度副词如often, always, every week, twice等连用。 I have been to the Summer Palace twice. 我曾经去过颐和园两次。
He has always said so.他总是这么说.
三.现在完成时的时间状语
I a. 用副词already和yet。already一般用于肯定句中，yet一般用于否定句和疑问句中。
如：We have already finished our homework.我们已完成作业了。
They haven't finished their homework yet.他们还没有完成作业。
b. 用ever和never.多用于否定或疑问句中，表示“曾经”或“从未“等。 如： -Have you ever been to the Great Wall?你曾经去过长城吗?
-I have never been to the Great Wall.我从未去过长城。
c. 用表示到说话为止的过去时间状语，如just, before, up to now, the past few years等。
例如：I have seen her before,but I can not remember where. 我以前见过她，但记不起在哪里见过。
He has been there three times the last few days. 近几天他去过那里三次了。 d.用包括“现在”在内的时间状语，如now,today,this morning(month,year,term)等。例如：-Have you met him today?-No,I haven't. 今天你见过他吗？我没有。
How many times have you been there this year? 今年你去过那里多少次？ II短暂性动词不能和表一段时间的时间状语连用。如：come, go, arrive, reach, hear, close, leave, begin, start, lose, buy, fall, join, die, get up等。但如果要保留表一段时间的时间状语，必须将动词改为延续性动词。
现归纳总结一下由非延续性动词到延续性动词的转换
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 +名词 finish( end )→be over
leave, move →be away, 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.他参军三年了。
His father has been dead for two years.他父亲去世二年了。
The film has been on for 5 minutes.电影已开始五分钟了。
We have studied English for three years. 我们（开始）学英语已三年了。
四.几点注意事项
I. have been(to)与have gone( to)的区别：
have been(to)表示“去过某地（现在已经回来了）”，可用于各人称；
have gone(to)表示“去某地了（说话时某人不在当地）”，常用于第三人称， 前者可与once ,never,several times等连用，后者则不能。
如： They have been to Beijing twice.他们去过北京两次。
He has gone to Beijing . 他去北京了。
II.不可延续性动词现在完成时的否定式，已变成一种可以延续的状态，因此可以和表示一段时间的状语连用。
如： I haven't left here since 1997.自从1997年以来，我一直没有离开过这儿。 （错）I have received his letter for a month.
（对）I haven't received his letter for almost a month.
练习一.用since和for填空
1.______two years 2.____two years ago
3.___last month 4.______ 1999
5._______yesterday 6._______ 4 o’clock
4 hours 8._____an hour ago
9.___we were children 10._____ lunch time
11.____ she left here
12. He has lived in Nanjing ___ the year before last.
13. I’ve known him ______ we were children.
14. Our teacher has studied Japanese ______ three years.
15. She has been away from the city ______ about ten years.
16. It’s about ten years __________ she left the city.
二.单项选择。
1、Both his parents look sad . Maybe they ______what's happened to him .
A. knew B. have known C. must know D.will know
2、He has _______ been to Shanghai , has he ?
A. already B.never C.ever D.still
3、Have you met Mr Li ______？
A. just B. ago C.before D. a moment ago
4、The famous writer _____ one new book in the past two year .
A. is writing B.was writing C.wrote D.has written
5、—Our country ______ a lot so far .
—Yes . I hope it will be even ______ .
A.has changed ; well B.changed ; good C.has changed ; better D.changed ; better
6、Zhao Lan ______already ______in this school for two years .
A. was ; studying B. will ; study C. has ; studied D. are ; studying
7、We ______ Xiao Li since she was a little girl .
A. know B. had known C. have known D. knew
8、Harry Potter is a very nice film .I______ it twice .
A.will see B.have seen C.saw D.see
9、—These farmers have been to the United States .
—Really ? When _____ there ?
A. will they go B. did they go C. do they go D. have they gone
10、—______ you ___ your homework yet ?
—Yes . I _____ it a moment ago .
A.Did ; do ; finished B.Have ; done ; finished
C.Have ; done ; have finished D.will ; do ; finish
三：用适当的时态填空：
1.She’s _____________ (live) here ever since she was ten.
2.Both of them ________________ (be) in Hongkong for ten days.
3.Both of them ____________ (come) to Hongkong ten days ago.
4. Half an hour __________ (pass) since the train __________ (leave).
5. Mary________(lose) her pen. ________ you _______(see) it here and there?
6. _________ you _____ (find) your watch yet?
7. ---Are you thirsty? ---No I _________just _________ (have) some orange.
8. We already _________ (return) the book.
9. ________ they _______ (build) a new school in the village?
10. I _____________(not finish) my homework . Can you help me?
11. My father _____ (read) the novel twice.
12. I _________ (buy) a book just now.
13. I _________ (lost ) my watch yesterday.
14. My father ___________ (read) this book since yesterday.
现在完成进行时
1 定义:现在完成进行时表示动作从过去某一时间开始，一直延续到现在，可能还要继续下去。
2构成:现在完成进行时是由“have/has+been+动词的现在分词”构成
3. 现在完成时的用法
1）在强调指出动作还未结束，还要继续下去。如：I've been reading this book for two hours，but I haven't finished it. 这本书我已读了两个小时了，但我还没读完。 I've read this book.我已读完这本书了。
2）强调动作延续时间的长久或带感情色彩。
She has always been working like that.她一贯是这样工作的。
3）现在完成进行时也可表示现在以前这段时间反复发生的事情。
We've been seeing quite a lot of each other recently.最近我们经常见面。 5 现在完成时和现在完成进行时的区别
1）现在完成进行时更强调动作的延续性,它是现在完成时的强调形式。试比较： We've been living here for ten years.
We've lived here for ten years.我们在这儿已经住了十年了。
2）在不用时间状语的情况下，现在完成进行时表示动作仍在进行。而现在完成时则表示动作在过去已结束。如：
The students have been preparing for the exam.（还在进行）学生们一直在准备考试。
The students have prepared for the exam.（已经结束）学生们为考试作了准备。
3）有些表示状态，感情，感觉的动词如：have，exist，like，hate，hear，know，sound等动词不能用于现在完成进行时，但可用于现在完成时。如： They've known each other since 1970.自从1970年起他们就相互认识了。 练习:
1.Mr Li swimming for 3 hours, and his son an hour ago.
A.has been, started B.have started, has started
C.started, started D. Has started, has started
2.---How long you stamps?
---Since two years ago.
A.have, collect B.have, been collecting C.did, collect D.are, collecting
3.She had a headache because she too long. She ought to shop.
A.has been reading B.had read C.is reading D.read
4.The boy TV all the morning.
A.has watched B.had watched C.has been watching D.watched
have you been learning to swim? ---Half a year.
A.How long B. How often C.How far D.When
6.Our teacher has been teaching in this school for .
A.two year and a half B.two and a half year
C.two years and half D.two and a half years
7.He it for two hours, and he's still watching now.
A.has been watched B.watching C.has been watching
D.is watching