for - since - ago

For - since - ago are used to talk about time
For is used to say how long an action or situation lasts.



*For is used with the Present Perfect :


- I have been waiting at the bus stop for 10 minutes.

- I have lived in this country for 10 years.



*For can also be used with other tenses :


- Present : I go on holidays for two weeks every year in the summer.

- Past : When I was sixteen, I stayed in London for two months.

- Future : During my trip to California next month, I will be in San Diego for two days.



Since is used to refer to the starting point of actions or situations.

It is generally used with the Present Perfect.


* I have been waiting for the bus since 8 o'clock.

* I live in Tokyo. I have lived in Tokyo since September 2000.


Ago is used to say when past events happened, going back from today towards the past.


* I came to Tokyo three years ago.

* I arrived at the bus stop ten minutes ago.

* I visited New York two years ago.

from: Learn English Today

Present Perfect Tense 1-2

Present Perfect Simple

Affirmative

I have done

You have done

He/she/is has done

We have done

They have done

You have done

Negative

Long Form Contracted Form

I have not done I haven't done

You have not done You haven't done

He/she/it has not done He/she/it hasn't done

We have not done We haven't done

You have not done You haven't done

They have not done They haven't done

Interrogative

Have I done?

Have you done?

Has he/she/it done?

Have we done?

Have you done?

Have they done?

from: LEARN ENGLISH TODAY

Perfect Present - Past Simple

(I have finished) (I finished)

When do we use them?

PRESENT PERFECT

The Present Perfect is used to link the present and the past.

The Present Perfect is used :

1. To talk about an action which started in the past and continues today.

For and since are used to express duration.

◊ I have lived here for 10 years. I have lived here since 1998.

(I arrived here 10 years ago and I am still here.)

2. To refer to past events in an unfinished period of time :

◊ I have written two letters today.

(Two letters are written but today is not finished.)

3. To talk about recent events that have just happened or been announced :

◊ There has been a plane crash near the coast.

(We know the event took place but we don't know when.)

4. To talk about a past action with a result in the present :

◊ I've broken my arm. I can't drive. (= because my arm is broken now)

5. To talk and ask about experiences or accomplishments up to the time of speaking, but at no specific time.

" I'm a writer. I've written 9 books."

" Have you ever written a biography?" "No never."

PAST SIMPLE

The Past Simple is used to talk about past events which happened in a finished period of time.

The Past Simple is used :

1. When the period of time is finished :

◊ I wrote two letters yesterday.

(Yesterday is finished.)

2. When the time is mentioned, either a precise time in the past, or a time expression which clearly situates the event in the past:

◊ I lived in the country

... until the age of 6

... when I was young

... from 1985 to 1992

... before we moved to London

... a long time ago

NB : As a general rule, if you can answer the question "when?", use the Past Simple

FROM: LEARN ENGLISH TODAY

Present Perfect

FORM

[has/have + past participle]

Examples:

You have seen that movie many times.
Have you seen that movie many times?
You have not seen that movie many times.

Complete List of Present Perfect Forms

USE 1 Unspecified Time Before Now

We use the Present Perfect to say that an action happened at an unspecified time before now. The exact time is not important. You CANNOT use the Present Perfect with specific time expressions such as: yesterday, one year ago, last week, when I was a child, when I lived in Japan, at that moment, that day, one day, etc. We CAN use the Present Perfect with unspecific expressions such as: ever, never, once, many times, several times, before, so far, already, yet, etc.

Examples:

I have seen that movie twenty times.
I think I have met him once before.
There have been many earthquakes in California.
People have traveled to the Moon.
People have not traveled to Mars.
Have you read the book yet?
Nobody has ever climbed that mountain.

A: Has there ever been a war in the United States?B: Yes, there has been a war in the United States.
How Do You Actually Use the Present Perfect?

The concept of "unspecified time" can be very confusing to English learners. It is best to associate Present Perfect with the following topics:

TOPIC 1 Experience

You can use the Present Perfect to describe your experience. It is like saying, "I have the experience of..." You can also use this tense to say that you have never had a certain experience. The Present Perfect is NOT used to describe a specific event.

Examples:

I have been to France.This sentence means that you have had the experience of being in France. Maybe you have been there once, or several times.
I have been to France three times.You can add the number of times at the end of the sentence.
I have never been to France.This sentence means that you have not had the experience of going to France.
I think I have seen that movie before.
He has never traveled by train.
Joan has studied two foreign languages.

A: Have you ever met him?B: No, I have not met him.

TOPIC 2 Change Over Time

We often use the Present Perfect to talk about change that has happened over a period of time.

Examples:

You have grown since the last time I saw you.
The government has become more interested in arts education.
Japanese has become one of the most popular courses at the university since the Asian studies program was established.
My English has really improved since I moved to Australia.

TOPIC 3

Accomplishments

We often use the Present Perfect to list the accomplishments of individuals and humanity. You cannot mention a specific time.

Examples:

Man has walked on the Moon.
Our son has learned how to read.
Doctors have cured many deadly diseases.
Scientists have split the atom.

TOPIC 4

An Uncompleted Action You Are Expecting

We often use the Present Perfect to say that an action which we expected has not happened. Using the Present Perfect suggests that we are still waiting for the action to happen.

Examples:

James has not finished his homework yet.
Susan hasn't mastered Japanese, but she can communicate.
Bill has still not arrived.
The rain hasn't stopped.

TOPIC 5

Multiple Actions at Different Times

We also use the Present Perfect to talk about several different actions which have occurred in the past at different times. Present Perfect suggests the process is not complete and more actions are possible.

Examples:
The army has attacked that city five times.
I have had four quizzes and five tests so far this semester.
We have had many major problems while working on this project.
She has talked to several specialists about her problem, but nobody knows why she is sick.
Time Expressions with Present Perfect
When we use the Present Perfect it means that something has happened at some point in our lives before now. Remember, the exact time the action happened is not important.

Sometimes, we want to limit the time we are looking in for an experience. We can do this with expressions such as: in the last week, in the last year, this week, this month, so far, up to now, etc.


Examples:

Have you been to Mexico in the last year?
I have seen that movie six times in the last month.
They have had three tests in the last week.
She graduated from university less than three years ago. She has worked for three different companies so far.
My car has broken down three times this week.

NOTICE

"Last year" and "in the last year" are very different in meaning. "Last year" means the year before now, and it is considered a specific time which requires Simple Past. "In the last year" means from 365 days ago until now. It is not considered a specific time, so it requires Present Perfect.

Examples:

I went to Mexico last year.I went to Mexico in the calendar year before this one.
I have been to Mexico in the last year.I have been to Mexico at least once at some point between 365 days ago and now.

USE 2
Duration From the Past Until Now (Non-Continuous Verbs)

With Non-Continuous Verbs and non-continuous uses of Mixed Verbs, we use the Present Perfect to show that something started in the past and has continued up until now. "For five minutes," "for two weeks," and "since Tuesday" are all durations which can be used with the Present Perfect.

Examples:

I have had a cold for two weeks.
She has been in England for six months.
Mary has loved chocolate since she was a little girl.
Although the above use of Present Perfect is normally limited to Non-Continuous Verbs and non-continuous uses of Mixed Verbs, the words "live," "work," "teach," and "study" are sometimes used in this way even though they are NOT Non-Continuous Verbs.

ADVERB PLACEMENT

The examples below show the placement for grammar adverbs such as: always, only, never, ever, still, just, etc.
Examples:
You have only seen that movie one time.
Have you only seen that movie one time?

ACTIVE / PASSIVE

Examples:

Many tourists have visited that castle. Active
That castle has been visited by many tourists. Passive

from: ENGLISH PAGE