1. The present perfect often links a present situation with something that happened at an unspecified time in the past. (Specific time expressions such as yesterday, last week, in 2003 etc. are used with past simple):
We have been here since March.
I have forgotten your name.
2. The present perfect is often used with the word “just” to talk about very recent news or actions:
I am not hungry now. I have just had lunch.
“Can I speak to Jane?” “I am afraid she has just left.”
3. The present perfect is often used with “already” and “yet”: Already is often used in positive sentences and indicates that something has taken place slightly earlier than expected. Yet is used in questions and negative sentences. It shows that we expect that an action will take place if it has not happened up to now.
Have you found a job yet ?
They have already decorated the room.
4. The present perfect is often used with words or phrases indicating periods of time that have not finished yet. Some common examples are: so far, up to now, today, this morning, this year, recently.
They have won five games this year.
We have found many new customers recently.
5. We also use the Present Perfect to talk about several different actions which occurred in the past at different times. Present Perfect suggests the process is not complete and more actions are possible.
They have been to Italy twice. - They can go to Italy again.
He has read ten books this year. – He can read some more books.
(!)In British English, the use of Simple Past and Present Perfect is quite strict. As soon as a time expression in the past is given, you have to use Simple Past. If there are no signal words, you must decide if we just talk about an action in the past or if it's consequence in the present is important. Note that English Portal exercises refer to British English only. In American English, you can normally use Simple Past instead of Present Perfect. We cannot accept this in our exercises, however, as this would lead to confusions amongst those who have to learn the differences.