have/has+过去时是什么时态

现在完成时是英文时态的一种
现在完成时的用法
主语+have(has)+过去分词(done)
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.
I have lost my wallet.(含义是:现在我没有钱花了.)
Jane has laid the table.(含义是:已可以吃饭了.)
Michael has been ill.(含义是:现在仍然很虚弱)
He has returned from abroad. (含义是:现在已在此地)
2. 现在完成时可以用来表示发生在过去某一时刻的,持续到现在的情况,常与for,since连用.
Mary has been ill for three days.
I have lived here since 1998.
3. 现在完成时往往同表示不确定的过去时间状语连用,如already, yet, just, before, recently,still, lately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
4. 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.
5. 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, now, 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 bee 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.
6. 现在完成时表示现在之前业已完成的动作,虽然其效果或影响仍然存在但已不再继续,但是有一些现在完成时的句子,在后面加上for+一段时间,则现在完成时的动作就表示延续性.
Thomas has studied Russian. (现在不再学俄语)
Thomas has studied Russian for three years. (=Thomas began to study Russian three years ago, and is still studying it now.(同第2点用法第一个例句)
7. 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.

现在完成时的“完成用法”和“未完成用法”
1.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?
2.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.
(2)现在完成时常见两种句型：
①for短语
②It is＋一段时间＋ since从句
3.一段时间+has passed+since从句
4.主语＋have / has been＋since短语
例如：He has been in the League for three years.或It is three years since he joined the League. 他入团已三年了
一.have/has been doing sth.
1.现在完成进行时
当后面接有一段时间的词时,或是加表示时间的词时,可以用现在完成时.如果这件事现在还在持续或还在做,则可用
现在完成进行时.
如:I have been skating for 4 hours.
I have finished my homework.
2.现在完成时的被动语态.
后接动词的过去分词.
如:The building has been built for 5 years.
二.一般现在时:用动词原形
一般过去时:用动词的过去式
一般将来时:will/shall+do
is/am/are going to do
过去将来时:could/would do
现在完成时:have/has done
过去完成时:had done
将来完成时:shall have done
过去将来完成时:would/could have done
现在进行时:is/am/are doing
过去进行时:was/were doing
将来进行时:will/shall be doing
过去将来进行时:would/could be doing
现在完成进行时:have/has been doing
过去完成进行时:had been doing
将来完成进行时:shall have been doing
过去将来完成进行时:would have been doing
此时态一般在中学学习
过去分词的构成：
1 、规则动词：规则动词的过去分词的构成规则与规则动词的过去式的构成规则相同.四点变化规则：
⑴、一般动词,在词尾直接加“ ed ”.
work---worked---worked ,visit---visited---visited
⑵、以“ e ”结尾的动词,只在词尾加“ d ”.
lived---lived---lived ,
⑶、以“辅音字母 + y ”结尾的动词,将 "y" 变为 "i" ,再加“ ed ”.
study---studied---studied ,cry---cried---cried ,
play---played---played ,stay---stayed---stayed
⑷、重读闭音节结尾,末尾只有一个辅音字母,先双写该辅音字母,再加“ ed ”.
stop---stopped---stopped , drop---dropped--dropped
2 、不规则动词：不规则动词的过去分词要特别牢记,详见课后附录中的不规则动词表.
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.
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 ）句强调的是他做着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.
（2）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.
（3）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 live 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）
出自百度百科
http://baike.baidu.com/view/191047.htm