Present perfect

The present perfect is one of the most misunderstood tenses since it's so tricky to pin down. Is it in the past or the present, for example, and when do we need to use it?

My boss said when he was doing his DELTA that his trainer berated him for saying the present perfect is something that happened in the past but is still true now. Heard that one before?

The form is:

S (I/You/We/It etc.) + has/have + past participle

So what does it describe?

1). It's mainly used to say an event in the past is connected with the present

I’ve already been to Japan, so I’m not going this time

2). Or to express something has been completed, or something has been achieved:

She has finished the race!; Have you completed your homework yet?; I have eaten my dinner

3). The present perfect isn’t used if it isn’t relevant to the present though, which is its distinction with the past simple. Compare the following sentences about the biologist Charles Darwin:

In this example, it argues that many scholars, since the time Darwin first said his theory, have thought he was incorrect.

Compare this with the following:

This example talks about one separate moment where scholars thought Darwin was incorrect. Any of the bendy lines could be the one moment when lots of scholars disagreed with Darwin, or where one scholar thought Darwin was incorrect.

The difference then between the past simple and present perfect is the present perfect talks about a period of time up until the present, whereas the past simple describes one moment in the past.

4). To state news of something that happened recently:

Grandad has had another heart attack; The World Trade Centre has just been attacked!; Spurs have won for the tenth straight time this season

The past simple then adds information:

Grandad has had another heart attack. He felt pain in his chest so Granny took him to the hospital

The World Trade Centre has just been attacked! Terrorists flew planes into the buildings

Spurs have won for the tenth straight time this season. They beat Arsenal 10 nil

5). Some of the time expressions used with the present perfect are “just, recently, lately, already, before, so far, still, ever/never, today, this morning/evening, for weeks/years, since 1988” (Oxford Guide to English Grammar p,93):

I’ve just eaten dinner; We have seen each other before; John and Dorro have been friends since 1988