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怎样区分现在完成时和过去式

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怎样区分现在完成时和过去式
如题
怎样区分现在完成时和过去式
现在完成时是英文时态的一种
现在完成时的用法
have(has)+过去分词(done)
1.现在完成时用来表示现在之前已发生活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, 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.


2. 对比
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:
①主语+have / has been+for短语
②It is+一段时间+ since从句
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
一般过去时表示(1)过去某个特定时间发生,并且一下子就完成了的动作(即:非持续性动作),也可以表示(2)过去习惯性的动作.一般过去时不强调动作对现在的影响,只说明过去.
I had a word with Julia this morning.今天早晨,我跟朱丽亚说了几句话.(1)
He smoked many cigarettes a day until he gave up. 他没有戒烟的那阵子,烟抽得可凶了.(2)
一般过去时常与表示过去的时间状语或从句连用,如:yesterday, last week, in 1993, at that time, once, during the war, before, a few days ago, when 等等.
2. 举例
句子中谓语动词是用一般过去时还是用现在完成时,取决于动作是否对现在有影响.
Have you had your lunch? 你吃过午饭了吗?(意思是说你现在不饿吗?)
Yes, I have. 是的,我已经吃过了.(意思是说已经吃饱了,不想再吃了.)
When did you have it? 你是什么时候吃的?(关心的是吃的动作发生在何时.)
I had it about ten minutes ago. 我是大约十分钟以前吃的.
Used to do something 表示过去常做而现在已经停止了的习惯动作.
I used to work fourteen hours a day. 过去常常一天干十四个小时.