Present Perfect

USES:
- To talk about ongoing actions that began in the past and are still going on: FOR, SINCE.
- To talk about recently completed actions: JUST.
- To talk about actions in the same period of time.

FORM:

- AFFIRMATIVE: Have + Verb in participle             *Third person singular use has*
I have played basketball since highschool.          She has played basketball since highschool.

- NEGATIVE: Have not + verb in participle       I haven't played.
                          Has not + verb in participle        She hasn't play football.

- QUESTION: Have + Subject + Verb infinitive + Complements?         Have you ever played tennis?
                          Has + Subject + Verb infinitive + Complements?          Has she ever played tennis?

TO HAVE is the auxiliary verb.

FOR Vs SINCE

FOR: To talk about a period of time: We have lived in this house for 3 months.

SINCE: To say when the action began: We have lived in this house since February.

JUST / ALREADY / YET

JUST: For something that happened a very short time ago: We have just finished our homework.

ALREADY: For something that happened before now - often a surprised: We have already get the house.

YET: For something that has not happened and questions: Mom hasn´t come back yet.

Links to exercises:
Present perfect 1
Present perfect 2
Present perfect 3
Present perfect 4
Present perfect 5
Present perfect 6