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.
Here is also a link to a PPT presentation: http://www.slideshare.net/guestbfc1f5/present-perfect-power-point
