The present perfect tense is formed by combining the auxiliary HABER with the participle of any verb, and express an action that has no definite time in the past.
USE 1 Unspecified Time Before Now
With the perfect present two verbs are in use: the corresponding form of the verb " to have " as verbauxilar and the form " past participle " of the principal verb.
• You have seen that movie many times.
• Have you seen that movie many times?
• You have not seen that movie many times.
Unspecified Time Before Now:
We use the Present Perfect to say that an action happened at an unspecified time before now. Theexact 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.
• I have seenthat movie twenty times.
• I think I have met him once before.
• There have been many earthquakes in California.
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 yourexperience. 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.
• 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 Francethree 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.
TOPIC 2 Change Over Time
We often use the Present Perfect to talk about change that has happened over a period of time.
• You have grown since the last time I saw you.
• Thegovernment has become more interested in arts education.
TOPIC 3 Accomplishments
We often use the Present Perfect to list the accomplishments of individuals and humanity. You cannot mention a specific time.
• Man has walked on the Moon.
• Our son has learned how to read
TOPIC 4 An Uncompleted Action You Are Expecting
We often use the Present Perfect to say that anaction which we expected has not happened. Using the Present Perfect suggests that we are still waiting for the action to happen.
• James has not finished his homework yet.
• Susan hasn't mastered Japanese, but she can communicate.
• Bill has still not arrived.
TOPIC 5 Multiple Actions at Different Times
We also use the Present Perfect to talk about severaldifferent actions which have occurred in the past at different times. Present Perfect suggests the process is not complete and more actions are possible.
• The army has attacked that city five times.
• I have had four quizzes and five tests so far this semester.
"Last year" and "in the last year" are very different in meaning. "Last year" means the year before now, andit 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.
• 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...