现在完成时
用法
（1）现在完成时用来表示现在之前已发生过或完成的动作或状态，但其结果却和现在有联系，也就是说，动作或状态发生在过去但它的影响现在还存在，也就是说，动作发生在过去，而对现在造成的影响和结果.
I have spent all of my money.（现在我没有钱花了.)
Jane has laid the table.（简已经摆好了桌子）
Michael has been ill.（迈克尔现在仍然很虚弱）
He has returned from abroad. （他现在已从国外回到此地）
（2）现在完成时可以用来表示发生在过去某一时刻的，持续到现在的动作（用行为动词表示）或状态（be动词表示）常与for（+时间段），since（+时间点或过去时的句子）连用.
①for+时段 为…时间
②since+过去一个时间点（译为：自从……以来）
③since+时段+ago
④since+从句（过去时）
⑤It is+时段+since+从句（过去时）
Mary has been ill for three days.
I have lived here since 1998.
注：瞬间动词（buy,die,join,lose……）不能直接与for since 连用。要改变动词
come/arrive/reach/get to-----be in
go out----be out
finish----be over
open----be open
die----be dead
Buy---have
Fall ill---be ill
Come back---be back
Put on ---be on/wear
Worry---be worried
Catch a cold---have a cold
⑥介词by在完成时态中用于表示截止日期
………………
★1.have代替buy
My brother has had（不能用has bought) this bike for almost four years.
★2、用keep或have代替borrow
I have kept（不能用have borrowed) the book for quite a few days.
★3、用be替代become
How long has your sister been a teacher?
★4、用have a cold代替catch a cold
Tom has had a cold since the day before yesterday.
★5、用wear代替put on
b）用“be+形容词”代终止性动词
1、be+married代marry 2、be+ill代fall (get) ill
3、be+dead代die 4、be+asleep代fall (get) asleep
5、be+awake代wake/wake up 6、be+gone代lose,die,sell,leave
7、be+open代open 8、be closed代close/shut
9、be+missing(gone,lost）代lose
c）用“be+副词”代终止性动词
1“be+on”代start,begin
2“be+up”代get up
3“be+back(to）”代return to,come back to,go back to
4“be here (there）”代come(arrive,reach,get) here或go (arrive,reach,get) there等等
d）用“be+介词短语”代终止性动词
1.“be in/at +地点”代替go to /come to
2.用be in the army 代替join the army
3.“be in/at +地点”代替move to
编辑本段
常用瞬间动词变延续性动词表
常用短暂性动词变延续性动词表+相应的介词：
1. have arrived at/in sw. got to/reached sw. come/gone/moved to sw. ——have been in sw./at…
2. have come/gone back/returned ——have been back
3. have come/gone out ——have been out
4. have become ——have been
5. have closed / opened ——have been closed/opened
6. have got up ——have been up；
7. have died ——have been dead；
8. have left sw. ——have been away from sw.
9. have fallen asleep/got to sleep —— have been asleep；
10. have finished/ended/completed ——have been over；
11. have married ——have been married；
12. have started/begun to do sth. —— have done sth. ；
13. have begun ——have been on
14. have borrowed/bought ——have kept/had
15. have lost ——haven’t had
16. have put on ——have worn
17. have caught /get a cold ——have had a cold；
18. have got to know —— have known
19. have/has gone to ——have been in
20.come to ——be in
21. have joined/have taken part in the league/the Party/the army —— have been a member of/ have been in/have been the Party’s member/the league member/the soldier…
Ⅰ.强调过去的行为对现在的影响。
eg.The young man has joined the army. 那位年轻人参军了。
编辑本段
用法注意
1.现在完成时不能单独与准确时间连用，（如表示过去的时间状语）
如yesterday(morning、afternoon),last(morning、afternoon）等，除非与for,since连用.
2.现在完成时往往同表示不确定的过去时间状语连用
如already（肯定），yet（否定，疑问），just,before,recently,still,lately,never等：
He has already obtained a scholarship.
I haven't seen much of him recently (lately).
We have seen that film before.
Have they found the missing child yet
3. 现在完成时常常与表示频度的时间状语连用，
如often,sometimes,ever,never,twice,on several occasion等：
Have you ever been to Beijing
I have never heard Bunny say anything against her.
I have used this pen only three times. It is still good.
George has met that gentleman on several occasions.
4. 现在完成时还往往可以同包括现在时间在内的时间状语连用，
如now,up to these few days/weeks/months/years,this morning/week/month/year,just,today,up to present,so far等：
Peter has written six papers so far.
Man has now learned to release energy from the nucleus of the atom.
There has been too much rain in San Francisco this year.
The friendly relations and cooperation between our two countries have been enhanced in the past few years.
Up to the present everything has been successful.
5. 现在完成时还可以用来表示过去的一个时间到现在这段时间内重复发生的动作.We have had four texts this semester.
6.现在完成时的"完成用法"
现在完成时的"完成用法"指的是动作发生在过去某一时刻并已结束，但该动作对现在产生了影响，与现在情况具有因果关系。
例如：He has turned off the light.他已把灯关了。（动作结束于过去，但说明的是现在的情况--灯现在不亮了。）
现在完成时"完成用法"的特点是动作不延续，因此，该时态只能与表示不定的过去时间状语（如：already，yet，before，recently等）、频度时间状语（如：never，ever，once等）、包括现在时刻在内的时间状语（如：this morning / month /year...，today等）连用。
例如：Have you found your pen yet？你已找到你的钢笔了吗？
7.现在完成时的"未完成用法"
现在完成时的"未完成用法"指的是动作开始于过去某一时刻，一直延续到现在，或可能还要继续下去。
例如：He has lived here since 1978.自从1978年以来，他一直住在这儿。（动作起始于1978年，一直住到现在，可能还要继续住下去。）
I have been in the army for more than 5 years.我在部队已经呆了五年多了。（动作开始于5年前，一直延续至今，有可能还要继续下去。）
此种用法的句中常需一个表示一段时间的状语（由since或for引导），或表示与现在时刻相连的时间状语（如：up to now，so far）等。
例如：I have heard nothing from him up to now.到目前为止我没有他的任何消息。
注意：（1）现在完成时的未完成用法只适用于延续性动词，不可用于终止性动词，即瞬间完成或延续时间很短的动词。如：come，go，arrive，leave，join，become，die等。
8.一段时间+has passed+since从句
9. 现在完成时常和短语 "up to now /till now","so far" （意思是从过去某一确定的时间一直延续到现在)连用。
Up to/till now he's read many story books. 至今他已读过好多故事书。
I've been to New York three times so far. 至今我已到纽约去过三次。
10 has gone (to),has been (to),has been (in) 的区别
gone：去了没回
been to ：去过
been in：呆了很久
10.不能与when连用
11.不可以与一般过去时的定义混淆
编辑本段
一般过去时和现在完成时
（ 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“主语+ have/ has + 动词（V.）的过去分词”。过去时表示过去某时发生的动作或单纯叙述过去的事情，强调动作；现在完成时为过去发生的，强调过去的事情对现在的影响，强调的是影响。
(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。
试比较以下几组句子，有什么区别：
① A:Have you seen the film
B:Did you see the film
分析：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 A:How has he done it
B:How did he do it
分析：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 A:He has lived in Beijing for 8 years .
B:He lived in Beijing for 8 years .
分析：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，现在已经不在北京了。
（3）现在完成时强调过去发生的动作对现在的影响和结果，而一般过去时与现在没有联系，只是说明某个动作发生的时间是在过去。
比：I have washed the car. 我洗过了车。（看上去很漂亮）
I washed the car a moment ago. 我刚才洗过车了。
She has watered the flowers. 她已经浇了花。（不需要再浇了）
She watered the flowers yesterday. 她昨天浇的花。
I have written the letter but I haven't posted it yet. 信我已经写好了，但还没有寄出。
I wrote the letter last week and I posted it three days ago. 我上周写的那封信，3天前寄出的。
（4）现在完成时表示的动作或状态延续到现在并可能延续下去，而一般过去时则单纯表示过去某段时间内的经历。
比：It has rained for five hours. 雨已经下了5个小时了。
It rained for five hours yesterday. 昨天下了5个小时的雨。
He has waited for her for two hours. 他等她已经两个小时了。
He waited for her two hours and then went home. 他等她等了两个小时，然后就回家了。
I have reviewed two lessons this morning. 今天上午我已经复习了两课。（说话时还在上午）
I reviewed two lessons this morning. 今天上午我复习了两课。（说话时已是下午或晚上）
编辑本段
现在完成时与现在完成进行时相同点
1. 在和一段时间状语连用时，现在完成时和现在完成进行时都可以表示从过去某一时刻开始一直延续到现在的动作.如：
I have worked in this school since 2001.
I have been working here since 2001.
2. 现在完成时和现在完成进行时都可以表示一段时间内进行的动作.例如：
Mr. Smith has taught English for 20 years.
Mr. Smith has been teaching English for 20 years.
以上句子用现在完成时与现在完成进行时，含义上没有什么差别，两种时态可以互相换.但两种时态也存在有意义上和用法上的差别.