The present perfect tense

The Present Perfect Tense
The Present Perfect Tense connects the past to the present. It describes an action that happened in the past and goes right to the present moment. The time of occurrence of the action is not mentioned. Usually, the time is not important or is not necessary to know. It is the result of the action that matters which may also come after the present moment.
To express something in the present perfect tense, it must use the simple present tense of the auxiliary verb have or has depending on whether the subject or noun being referred to is plural or singular. The auxiliary verb is followed by the past participle of the main verb (for example, regular verb: have called; irregular verb: has given).
• I have spent 20 years studying French.
• He has worked as an administrator for years.
• We have owned this house since 1985.
These examples indicate that the action began at a time before now. Additionally, these actions continue on into the present and will likely extend to the future.
Present Perfect Simple and Present Perfect Continuous
We use the present perfect tense to talk about things where there is a connection between the past and the present.
• He’s written 16 books.
He started writing books at some time in the past. So far, he has written 16 books. He may write more books.

As well as the present perfect simple, we can use the present perfect continuous tense to talk about events with a connection to the present.

1 Look at these 2 sentences:
• I’ve been decorating the house this summer. The focus is on the action – decorating – and the action is unfinished.
• I’ve painted the living room blue. The focus is on the finished result. The activity is finished but we can see the result now.
We use the present perfect continuous when the focus is on an activity that is unfinished.

2 Look at these two sentences.
• I’ve read that book you lent me. I finished it yesterday.
• I’ve been reading that book you lent me. I’ve got another 50 pages to read.
The present perfect simple (I’ve read) gives the idea of completion while the present perfect continuous (I’ve been reading) suggests that something is unfinished.

3 Look at these two sentences.
• She’s been writing emails for 3 hours.
• She’s written 10 messages.
The present perfect continuous (has been writing) talks about how long something has been happening. The present perfect simple (has written) talks about how much/how many have been completed.

4 Look at these two sentences.
• I’ve worked here for thirty years.
• I usually work in London but I’ve been working in Birmingham for the last 3 weeks.
We can use the present perfect simple to talk about how long when we view something as permanent. But the present perfect continuous is often used to show that something is temporary.