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Forum > Ngữ php tiếng Anh >> THE PRESENT PERFECT AND THE PRESENT PERFECT CONTINUOUS

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 Post by: lovelycat
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 ID 13802
 Date: 10/03/2006


THE PRESENT PERFECT AND THE PRESENT PERFECT CONTINUOUS
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1. Use of the present perfect


The English Present Perfect tense is used to express actions which have already been completed, or perfected, at the time of speaking or writing. In the examples given below, the verbs in the Present Perfect tense are underlined.

e.g. I have done the work.

She has answered half the questions.



In the first example, the use of the Present Perfect tense emphasizes the fact that, at the time of speaking or writing, the work has already been completed. In the second example, the use of the Present Perfect indicates that, at the time of speaking or writing, half the questions have been answered.

 


2. Formation of the present perfect: Regular verbs


The Present Perfect tense of any English verb is formed from the Simple Present of the auxiliary to have, followed by what is generally referred to as the past participle of the verb.



Most English verbs form the past participle in a regular, predictable manner. These verbs are commonly referred to as regular verbs.



The past participle of a regular English verb is formed by adding the ending ed to the bare infinitive of the verb. For instance, the past participle of the verb to work is worked.



Thus, the Present Perfect tense of the verb to work is conjugated as follows:




























I have worked
you have worked
he has worked
she has worked
it has worked
we have worked
they have worked



The following contractions are often used in spoken English:







































Without Contractions With Contractions
  I have   I've
  you have   you've
  he has   he's
  she has   she's
  it has   it's
  we have   we've
  they have   they've



It should be noted that the contractions for he has, she has and it has are the same as the contractions for he is, she is and it is.





3. Spelling rules for adding ed to form the past participle


Some regular verbs change their spelling when the ending ed is added to form the past participle.



a. Verbs ending in a silent e

When a regular verb ends in a silent e, only the letter d must be added in order to form the past participle. For example:



























Infinitive Past Participle
  to close   closed
  to move   moved
  to please   pleased
  to receive   received



b. Verbs ending in y

When a regular verb ends in y immediately preceded by a consonant, the y is changed to i before the ending ed is added. For example:























Infinitive Past Participle
  to study   studied
  to rely   relied
  to carry   carried



However, when a regular verb ends in y immediately preceded by a vowel, the y is not changed before the ending ed is added. For example:























Infinitive Past Participle
  to play   played
  to convey   conveyed
  to enjoy   enjoyed



c. Verbs ending in a single consonant preceded by a single vowel

The rules concerning the doubling of final consonants which apply when adding the ending ing to form the present participle also apply when adding the ending ed to form the past participle.



Thus, when a one-syllable verb ends in a single consonant other than w, x or y immediately preceded by a single vowel, the final consonant must be doubled before the ending ed



is added to form the past participle. In the following examples, the consonants which have been doubled are underlined. For example:























Infinitive Past Participle
  to rub   rubbed
  to trim   trimmed
  to plan   planned
  to stop   stopped



When a verb of more than one syllable ends in a single consonant other than w, x or y immediately preceded by a single vowel, the final consonant is doubled before the ending ed only when the last syllable of the verb is pronounced with the heaviest stress. In the following examples, the syllables pronounced with the heaviest stress are underlined. For example:















































Infinitive Past Participle
  to control   controlled
  to infer   inferred
  to occur   occurred
  to permit   permitted
   
  to fasten   fastened
  to order   ordered
  to focus   focused
  to limit   limited



In the first four examples, the last syllable of the verb is pronounced with the heaviest stress, and the final consonant is doubled before ed is added. In the last four examples, the first syllable of the verb is pronounced with the heaviest stress, and the final consonant is not doubled before ed is added.



The final consonants w, x and y are never doubled when the ending ed is added. For example:























Infinitive Past Participle
  to follow   followed
  to box   boxed
  to portray   portrayed



It should also be noted that final consonants immediately preceded by two vowels are not doubled when the ending ed is added. For example:



























Infinitive Past Participle
  to greet   greeted
  to rain   rained
  to soak   soaked
  to treat   treated

 


4. Pronunciation of the ed ending


The ending ed is usually not pronounced as a separate syllable. For instance, in each of the following examples, both the bare infinitive and the past participle consist of one syllable. For example:



























Bare Infinitive Past Participle
  puff   puffed
  work   worked
  miss   missed
  watch   watched



However, when the ending ed is added to verbs which end in d or t, the ed ending of the past participle is pronounced as a separate syllable. The reason for this is that the sounds of d and t are so similar to the sound of the ed ending, that the ending must be pronounced as a separate syllable in order to be heard clearly.



In each of the following examples, the bare infinitive consists of one syllable; whereas the past participle consists of two syllables. For example:



























Bare Infinitive Past Participle
  add   added
  land   landed
  hunt   hunted
  wait   waited



Similarly, when d is added to verbs ending in a silent e preceded by d or t, the final ed of the past participle is pronounced as a separate syllable. In each of the following examples, the bare infinitive consists of one syllable; whereas the past participle consists of two syllables. For example:



























Bare Infinitive Past Participle
  fade   faded
  glide   glided
  cite   cited
  note   noted




 


5. Formation of the present perfect: Irregular verbs


In addition to regular English verbs, there are many irregular English verbs, which do not form the past participle with the ending ed. The English irregular verbs are related to the strong verbs of the German language. The following are examples of irregular English verbs. For example:































Bare Infinitive Past Participle
  begin   begun
  find   found
  go   gone
  let   let
  take   taken



The past participles of irregular English verbs are formed in an unpredictable manner, and must be memorized. A table of common English irregular verbs is provided.



Except for the irregularity of the past participle, the formation of the Present Perfect tense is the same for an irregular verb as for a regular verb. In both cases, the Simple Present of the auxiliary to have is followed by the past participle of the verb.



For instance, the irregular verb to take has the past participle taken. Thus, the Present Perfect of the irregular verb to take is conjugated as follows:




























 I have taken
 you have taken
 he has taken
 she has taken
 it has taken
 we have taken
 they have taken

 


6. Questions and negative statements


As is the case with other English tenses, questions and negative statements in the Present Perfect are formed using the auxiliary. In the case of the Present Perfect, the auxiliary is have or has.



a. Questions

In order to form a question, the auxiliary is placed before the subject of the verb. For example:







































Affirmative Statement Question
  I have worked.   Have I worked?
  You have worked.   Have you worked?
  He has worked.   Has he worked?
  She has worked.   Has she worked?
  It has worked.   Has it worked?
  We have worked.   Have we worked?
  They have worked.   Have they worked?



b. Negative statements

In order to form a negative statement, the word not is placed after the auxiliary. For example:







































Affirmative Statement Negative Statement
  I have worked.   I have not worked.
  You have worked.   You have not worked.
  He has worked.   He has not worked.
  She has worked.   She has not worked.
  It has worked.   It has not worked.
  We have worked.   We have not worked.
  They have worked.   They have not worked.



The following contractions are often used in spoken English:



















Without Contractions With Contractions
  have not   haven't
  has not   hasn't



c. Negative questions

In order to form a negative question, the auxiliary is placed before the subject, and the word not is placed after the subject. However, when contractions are used, the contracted form of not follows immediately after the auxiliary. For example:







































Without Contractions With Contractions
  Have I not worked?   Haven't I worked?
  Have you not worked?   Haven't you worked?
  Has he not worked?   Hasn't he worked?
  Has she not worked?   Hasn't she worked?
  Has it not worked?   Hasn't it worked?
  Have we not worked?   Haven't we worked?
  Have they not worked?   Haven't they worked?




d. Tag questions

Tag questions are also formed using the auxiliary. In the following examples, the negative tag questions are underlined.







































Affirmative Statement Affirmative Statement with Tag Question
  I have worked.   I have worked, haven't I?
  You have worked.   You have worked, haven't you?
  He has worked.   He has worked, hasn't he?
  She has worked.   She has worked, hasn't she?
  It has worked.   It has worked, hasn't it?
  We have worked.   We have worked, haven't we?
  They have worked.   They have worked, haven't they?






 


7. The present perfect continuous


a. Use

The Present Perfect Continuous tense is used to express continuous, ongoing actions which have already been completed at the time of speaking or writing.



In the following example, the verb in the Present Perfect Continuous tense is underlined.

e.g. The bus has been waiting for one hour.



The use of the Present Perfect Continuous tense in this example indicates that, at the time of speaking or writing, the bus has completed one hour of continuous waiting.



b. Formation

The Present Perfect Continuous tense of any English verb is formed from the Present Perfect of to be, followed by the present participle of the verb. For instance, the Present Perfect Continuous tense of the verb to work is conjugated as follows:




























 I have been working
 you have been working
 he has been working
 she has been working
 it has been working
 we have been working
 they have been working



Thus, it can be seen that the Present Perfect Continuous tense has two auxiliaries. The first auxiliary is have or has, and the second auxiliary is been.



c. Questions and negative statements

When a verb has more than one auxiliary, it is the first auxiliary which must change its form to agree with the subject of the verb. It is also the first auxiliary which is used to form questions and negative statements.



Questions are formed by placing the first auxiliary before the subject of the verb. For example:







































Affirmative Statement Question
  I have been working.   Have I been working?
  You have been working.   Have you been working?
  He has been working.   Has he been working?
  She has been working.   Has she been working?
  It has been working.   Has it been working?
  We have been working.   Have we been working?
  They have been working.   Have they been working?



Negative statements are formed by placing the word not after the first auxiliary. For example:







































Affirmative Statement Negative Statement
  I have been working.   I have not been working.
  You have been working.   You have not been working.
  He has been working.   He has not been working.
  She has been working.   She has not been working.
  It has been working.   It has not been working.
  We have been working.   We have not been working.
  They have been working.   They have not been working.



Negative questions are formed by placing the first auxiliary before the subject, and the word not after the subject. However, when contractions are used, the contracted form of not



follows immediately after the first auxiliary. For example:




































Without Contractions With Contractions
  Have I not been working?   Haven't I been working?
  Have you not been working?   Haven't you been working?
  Has he not been working?   Hasn't he been working?
  Has she not been working?   Hasn't she been working?
  Has it not been working?   Hasn't it been working?
  Have we not been working?   Haven't we been working?
  Have they not been working?   Haven't they been working?



Tag questions are formed using the first auxiliary. In the following examples, the negative tag questions are underlined. For example:







































Affirmative Statement Affirmative Statement with Tag Question
  I have been working.   I have been working, haven't I?
  You have been working.   You have been working, haven't you?
  He has been working.   He has been working, hasn't he?
  She has been working.   She has been working, hasn't she?
  It has been working.   It has been working, hasn't it?
  We have been working.   We have been working, haven't we?
  They have been working.   They have been working, haven't they?


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