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现在完成时The Present Perfect Tense

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现在完成时The Present Perfect Tense

一、结构:

1.肯定句: +have/has + done

2.否定句: +have/has + not  + done

3.疑问句Have/has + + done?

          Yes, +have/has.

          No, +have/hasn't.

  助动词havehas可前面的主语缩略为've, 's. they've, we've, he's, it's;

          has not=hasn't   have not=haven't

 

二、过去分词的构成

1. +ed   work, plant,call

2.e+d   live, change, like, love, agree, save, hate, move, arrive,,skate, hope, use

3.以重读闭音节结尾,末尾只有一个辅音字母的 双写+ed.

  如:plan, stop, drop, fit(适合), prefer(更喜欢), travel

4。以辅音字母+y,结尾,变yied  try, study, carry, hurry, cry, worry, copy

 

三、用法:

1.表示过去发生的某一动作对现在造成的影响或结果。

   常与以下词连用,already, yet, just, now, 例如:

   I have just cleaned my clothes. 我刚洗过衣服。

洗衣服是发生在过去的动作,对现在造成的结果是衣服干净了

already (“已经,用在肯定句)

 I have already finished my homework.

yet已经”,用在疑问句;“用在否定句)

 Has he finished his homework yet?

 She hasn't finished her homework yet.

just (“刚刚,用在肯定句)

 We have just finished our homework.

now (现在)  I have had my breakfast now.

2. 表示说话前发生过一次或多次,而现在已成为经历或经验的动作或状态,常与以下词连用。

ever (“曾经,用在疑问句中)     Have you ever been to Hong Kong?

never (“从未表示否定)         I've never been there.

before (以前)                   He has seen her before.

once (“曾经”“一次,用在肯定句)  twice, three times…

                                She has been there once.

 

3.表示动作从过去已经开始,持续到现在的动作或状态,往往和表示一段的时间状语连用。

  for引导的时间段,since引导的过去时间点和含有过去时的从句,动词用持续性动词。

  have/has+过分(延续性动词) + for+一段时间,

                          +since+一段时间+ago

                   +since+时间点

We have learned English for five years.

We have learned English since five years ago.

I have been here since 5 o'clock.

现在完成时+ since+一般过去时

即:have/has+过分(延续性v)since从句(一般过去时)

  I have been here since I was young.

He has lived here since he came here.

短暂性动词与延续性动词

   短暂性动词也叫瞬间动词或终止性动词。这种动词是指它们动作的开始也就意味着动作的结束,所以不能跟表示一段的时间状语连用,象这样的词有:buy, sell, begin, start, leave, come, go, borrow, lend, return, die, join等。

延续性动词也叫持续性动词,能和一段时间连用。

1.短暂性动词和延续性动词都可用于现在完成时中

  have/has+过分(短暂性v)  (肯定句, 疑问句中,不能加一段时间)

  have/has not+过分(短暂性v)  (否定句,能加一段时间)

即:have/has not +过分(短暂性动词)  +for+一段时间,

                                  +since+时间点

                                  + since+一段时间,+ago 

have / has +过分(延续性动词)(可加一段时间),例如:

  She has died.(短暂性v,肯定句,不能加一段时间)

  She has been dead (for 5 years.)(延续性动词)

2.短暂性动词不能用于由for+一段时间, since+时间点(since…ago)引导的现在完成时的肯定句,疑问句中,此句型必须用延续性动词,

 have/ has+ 过分 (延续性动词)  + for+一段时间,

          (短暂性动词必须    +since+一段时间+ago

          转换成延续性动词)  +since+时间点

have/has+过分(延续性动词) +since从句(一般过去时)

3短暂性动词与时间段的关系

短暂性动词在肯定句、疑问句中不能与时间段连用,这些动词是:become, begin, buy, borrow, arrive, come, die, fall, finish, get to know, go, join, leave, marry等。为了表述这种意思,可用以下几种表示法:

(1) It is +一段时间+since从句(一般过去时 ) (短暂性动词)

(2) 一般过去时 (短暂性动词) + 一段时间+ago

还可用相应的延续性动词havekeep等或短语“be+名词(形容词、位置副词、介词短语)来代替短暂性动词,sincefor引导, (短暂性动词必须转换成延续性动词)

(3) have/has+过分(延续性动词) + for+一段时间,

(4)have/has+过分(延续性动词)+since+一段时间+ago

have/has+过分(延续性动词) +since+时间点

  have/has+过分(延续性动词)  + since从句(一般过去时) (短暂性动词)

(5) 一段时间+现在完成时+ since从句(一般过去时) (短暂性动词)

    Two weeks has passed sine he left Shanghai .

上面5句可相互替换:

   他离开学校已经20年了.

   1It is 20 years since he left the school.

   2He left the school 20 years ago.

   3He has been away from the school for 20 years.

   4He has been away from the school since 20 years ago.

   520 years has passed since he left the school.