Present Perfect Verb Tense
The present perfect is formed from the present tense of the verb have and the past participle of a verb:
subject + has/have + past participle
You have written that sentence before.
Have you written that sentence before?
You have not written that sentence before.
Let’s take a look at the ways in which the present perfect forms is used in sentences and phrases.
We use the present perfect form when we talk about an action which happened at an unspecified time before now. The exact time is not important. In fact, you do not use the present perfect with exact expressions of time like yesterday, last year, etc.
Present perfect is used with time adverbials referring to the recent past as well as the present, all being unspecific time expressions such as: ever, just, only just, recently once, so far, until now, many times, several times and yet (when used in questions.):
They have recently found a new species of butterfly.
We have just got back from Spain.
Have you ever seen a ghost?
Where have you been up to now?
Have you finished your book yet?
We use the present perfect to describe an experience, as in:
I have (or have not) the experience of.
I have been to San Francisco
We also use the present perfect to talk about change that has happened over a period of time. For example:
You have changed since you graduated from high school.
When we want to talk about accomplishments we often employ present perfect. There is no mention a specific time:
Researchers have found a cure for malaria.
The present perfect is the way we say that an action which we expected has not happened, and suggesting that we are still waiting for it to happen:
Jenny has not finished the race yet.
We also use the present perfect when we talk about many actions which have occurred in the past at different times, and we suggest that more actions of the same kind are possible:
The power has been disrupted seven times.
I have had three French lessons this week.
The other way in which present perfect can be used is with non-continuous verbs – we use the present perfect to show that something started in the past and has continued up until now. ‘For seven years,’ ‘since last year,’ are examples of durations which can be used with the present perfect.
So – you can see that the present perfect tense form is a very commonly used tense form in the English language.