The same form (have + past participle) exists in many languages, but the uses in English are different. In English, the Present Perfect expresses the effect of the past on the present.
Present Perfect means 'completed before now'. The Present Perfect does not express when an action happened. If we say the exact time, we use the Past Simple.
In my life, I have travelled to all the continents.I travelled around Africa in 1998.| + | – | ? | |
|---|---|---|---|
| I/you/we/they | 've lived in Rome. | haven't bought their flat | How long have you known Peter? |
| he/she/it | 's lived in London. | hasn't lived here long | How long has she been married? |
The Present Perfect expresses an action that began in the past and still continues.
We've lived in the same house for 25 years.We've been married for 20 years.Time expressions: for (with a period of time) and since (with a point in time).
| for | since |
|---|---|
| two years / a month / a few minutes / half an hour / ages | 1970 / August / 8.00 / I was a child / Christmas |
The Present Perfect expresses an experience at some time in one's life. The action is finished but the effects are still felt in some way.
I've been to the United States. (I know now what it's like there.)Have you ever had an operation?Time expressions: ever, never, before
The Present Perfect expresses a past action that has a clear present result.
The taxi hasn't arrived yet. (We're still waiting for it.)Have you heard? The Prime Minister has resigned.Time expressions: yet (negative/question), already (positive), just