Level: intermediate

We use perfect aspect to look back from a specific time and talk about things up to that time or about things that are important at that time.

We use the present perfect to look back from the present:

I have always enjoyed working in Italy. [and I still do]
She has left home, so she cannot answer the phone.

We use the past perfect to look back from a time in the past:

It was 2006. I had enjoyed working in Italy for the past five years.
She had left home, so she could not answer the phone.

We use will with the perfect to look back from a time in the future:

By next year I will have worked in Italy for 15 years.
She will have left home by 8.30, so she will not be able to answer the phone.

Present perfect

We use the present perfect:

  • for something that started in the past and continues in the present:

They've been married for nearly 50 years.
She has lived in Liverpool all her life.

  • when we are talking about our experience up to the present:

I've seen that film before.
I've played the guitar ever since I was a teenager.
He has written three books and he is working on another one.

  • for something that happened in the past but is important in the present:

I can't get in the house. I've lost my keys.
Teresa isn't at home. I think she has gone shopping.

We normally use the present perfect continuous to emphasise that something is still continuing in the present:

It's been raining for hours.
I'm tired out. I've been working all day.

Past perfect

We use the past perfect:

  • for something that started in the past and continued up to a later time in the past:

When George died, he and Anne had been married for nearly 50 years.
She didn't want to move. She had lived in Liverpool all her life.

  • when we are reporting our experience up to a point in the past:

My eighteenth birthday was the worst day I had ever had.
I was pleased to meet George. I hadn't met him before, even though I had met his wife several times.

  • for something that happened in the past and is important at a later time in the past:

I couldn't get into the house. I had lost my keys.
Teresa wasn't at home. She had gone shopping.

We use the past perfect continuous to show that something started in the past and continued up to a time in the past or was important at that time in the past:

Everything was wet. It had been raining for hours.
He was a wonderful guitarist. He had been playing ever since he was a teenager.

Modals with the perfect

We use will with the perfect to show that something will be complete at or before some time in the future:

In a few years they will have discovered a cure for the common cold.
I can come out tonight. I'll have finished my homework by then.

We use would with the perfect to refer to something that did not happen in the past:

If you had asked me, I would have helped you.
I would have helped you, but you didn't ask me.
You didn't ask me or I would have helped you.

We use other modals with the perfect when we are looking back from a point in time. The point of time may be in the future:

We'll meet again next week. We might have finished the work by then.
I will phone at six o'clock. He should have got home by then.

or the present:

It's getting late. They should have arrived by now.
He's still not here. He must have missed his train.

or the past:

I wasn't feeling well. I must have eaten something bad.
I checked my mobile phone. She could have left a message.

Perfect aspect 1

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Perfect aspect 2

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Perfect aspect 3

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Comments

Hi Khaled,
The difference you are asking about is explained on our page about the active and passive voices. But to understand the difference between the forms of the verb change in the sentences you mention, I would also recommend that you look at the section on ergative verbs on our page on reflexive and ergative verbs. There you will see that change is an ergative verb, i.e. a verb that can be both transitive and intransitive.
In sentence 2, change is an intransitive verb, whereas in sentence 1 it is a transitive verb in the passive voice. 
Please also note that in standard English, both of your sentences should say from one condition to another at the end. This minor error is not important to understanding the difference between the two sentences, but I wanted to mention it.
If you have any questions about this grammar, please don't hesitate to ask. If you do ask another question, would you please ask it on the active and passive voice page so that other users can benefit from your question as well?
Thanks for your collaboration.
Best wishes,
Kirk
The LearnEnglish Team
 

Hello,

I find it difficult to differentiate between the present perfect and the present perfect continuous . It says that both are used when talking about something continuing up to the present. For example, what is the difference between:" I have been working here for 3 years" and " I have worked here for 3 years"
thanks in advance

Hello zagrus,

Often with the verbs "live" and "work" there is no significant difference in meaning between the two verb forms. The continuous form emphasizes the action, and the perfective form emphasizes the completion of the action, but other than that they mean the same thing.

I also wanted to recommend our page on the present perfect, which could be helpful as well:
http://learnenglish.britishcouncil.org/en/english-grammar/verbs/present-...

Please don't hesitate to ask again if you have any more questions.

Best wishes,

Kirk
The LearnEnglish Team

Hi.
I don´t understand the diference between past and past perfect.
For example: 'He had worked...'. Why cannot I say 'He worked on....'.
I already read many things about this, but I don´t understand it.
Thanks
Zaida

Hi Zaida,

The past perfect form can only be understood in a context, not as an isolated phrase.  You can say both 'He had worked...' and 'He worked on...'; which is correct will depend upon the context.  Perfect forms are forms which look back on an earlier time, and the past perfect looks back on a time earlier in the past.  For example:

He worked on the report all night. [a time in the past]

He looked tired when I saw him because he had worked on the report all night. [looking back (from when I saw him) on a time earlier in the past (when he did was working)]

You can find more information on talking about the past here.

You can find more information on the past simple here.

You can find more information on the past perfect here.

I hope that helps to clarify it for you.

Best wishes,

 

Peter

The LearnEnglish Team

sir,

1. The result hasn't yet come.
2. The result hasn't been come yet. (passive)

Out of these two, which one is correct?
Could we use verbs like come with the subjects that don't have legs (can't come physically)?

please explain some more information of such subjects.

Thanks & Regards

Krishna

Hello Krishna,

Sentence 1 is correct and sentence 2 is not. This is because intransitive verbs (verbs which do not take an object) such as come are not used in the passive. I'd suggest you read the explanations on our active and passive voice page - I think this should clarify this for you.

Yes, come and other verbs can refer to movement in general, not just physical movement, whether by means of legs or any other apparatus.

Best wishes,

Kirk
The LearnEnglish Team

Thanks Kirk.

Hi there! I was told that when we use modal verbs ( should, would, must etc.) with perfect : It would have been = in this case the perfect is not the persent perfect but perfect infinitive, and it doesn't change in the 3rd person sg. Is that right? Could someone give me a short explanation about this? Thank's in advance :)

Hello Flora,

You are correct that the form in these constructions is not the present perfect but rather the past participle, also called the third form of the verb or the perfective form. (The explanation on the page describes it as 'the perfect', not the 'present perfect').  As you said, tt does not change form with the third person.

Best wishes,

 

Peter

The LearnEnglish Team

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