People try to dismiss this tense, but it has a very handy feature, namely signifying something that began or happened in the past but has an effect now.
Have you ever wondered why we say a sentence like this? What does it mean? The use of the word "ever" means "in your life until now", therefore shows something that began in the past and is still relevant at the time you say it.
We can use a continuous form or a simple form, illustrated below with another sentence to add context:
A. Last Friday, I bought a book.
B. I have been reading it on-and-off since then.
C. I have read 129 pages.
Here, we see the tenses in action. The past simple in A is used for a time no longer relevant to now. We nearly always need to say when you are talking about, like last Friday, unless it's obvious or the context has already been set, e.g. "Shakespeare lived in London for many years," or "the last World Cup was a triumph."
The present perfect continuous form in B signifies that the action of reading the book started in the past and continues now. The emphasis in this case is on how long? as the continuous form often puts the emphasis on an action or process, and not on a situation or state.
In C, the context shifts to exactly that - a situation or state. This is clear, as the speaker is saying how many pages he/she has read up until now.
Using the present perfect doesn't always mean the action or situation is complete, nor does it mean it is incomplete. It is just an indicator of the current state of the process or situation.
Let us look at various contexts in more detail:
1. There is a use for the present perfect where the most up-to-date information is used in the present perfect. For simplicity, I call this new news:
"Three men have escaped from a high-security prison in Cumbria. They fooled the night guards into believing they were sick with food poison and at the guards' most vulnerable moment, tied them to the prison rails. They are believed to be hiding in the forest near the prison."
"Damn, I've lost my pen. I left it on the table and went to the bathroom, and now it's gone!"
In the first, they are obviously still not back in the hands of the law. The rest is just relating the story, all of which happened in the past.
In the second, the pen is missing now. So both points related to that are in the present perfect. The middle part is the person thinking about the sequence of events leading up to it, and for that he/she needs the past.
2. We can use some words to signify our use of the present perfect, for example for, since, ever, and just.
FOR
We use for in the present perfect to signify a length of time, e.g.
"I have been here for four days."
This means you came four days ago.
But I can use this in other tenses too. Check out the difference:
A. "I stayed in the hotel for a week."
B. "I have been staying at this hotel for a week."
C. "I am staying at this hotel for a week."
A - this is of course part of a conversation about a time in the past. It probably needs "last summer" or some such information attached to it.
B - you are clearly there now, and arrived a week ago.
C - this is your plan, and bears no relation to when you arrived.
SINCE
We use since to determine a time you first arrived, and can only be used in the present perfect, both simple and continuous.
"I have lived here since July 1985."
"We have been sitting here since 3 o'clock."
EVER
In the present perfect, this is used to say in your life until now, and mainly in questions. It can of course be used in other tenses, as follows:
"Have you ever eaten an insect?"
"I wonder if Shakespeare ever visited Italy."
"I have my doubts if we will ever see world peace."
JUST
We use just to talk about what happened a few seconds ago, or is a moment we would say was extremely recent:
"Give us a moment to relax, we have just arrived!"
"Lucky we learned to drive before we moved here; the only supermarket in town has just closed down!"
So as you see, the present perfect is a very useful tense indeed, and like in everything we do, we should not translate tenses directly into our own languages as there is often a different way of handling these things. Always look at the context.
Keep learning!
