A present perfect tense is often used in subordinate clauses to show that one thing is completed before another starts. Note that the present perfect tense can be used in the subordinate clause only when the verb in the main clause is in the present or future tense.

The present perfect tense generally represents an action which has been completed within a period of time that extends up to and includes the present time.

Subject + transitive verb (present perfect) + object + adverbials or complements

Active sentences in the present perfect tense have the following structure:
Subject + has/have + past participle form of the verb + object
Passive sentences in the present perfect tense have the following structure:
Object of the active sentence + has/have + been + past participle form of the verb + by + subject of the active sentence

Common Errors with the Present present tense

‘Where is Alice?’ ‘She has been to the market.’ (Wrong)
She has gone to the market. (Right)

Explanation

The present perfect tense is used to represent an action which has been completed within a period of time that extends up to the present. The present perfect tense can also be used to talk about actions which cannot be attributed to a definite point of time.

Present Perfect Tense

Form
Affirmative
I have written.
He has written.
They/you/we have written.

Negative
I have not written.
She has not written.
They/you/we have not written.