English Tense: Present Perfect
(Subject + Has/have + III form of the verb)
(i) In the Present Perfect Tense the past participle (III)) form of the verb is used with has or have. ‘Has’ is added with third person singular subjects, as—‘he’, ‘she’, ‘it’ and ‘Have’ is added with ‘I’, ‘we’, ‘you’, ,’they’ and plural nouns.
He has won a prize.
You have insulted me.
I have taken the dose of medicine.
(ii) In Interrogative form [Has, have are placed before the subject.] (Has/have + Subject + III form of the Verb...?)
Have they crossed the river?
Where have you seen my brother?
(iii) In Negative form [‘not’ is used between the main verb and the helping verb.]
(Subject + has/have + not + III form of the Verb...)
She has not come yet.
I have not received any information.
Uses of the Present Perfect Tense
The Present Perfect Tense is used with the words: yet, as yet, already, just, just now, so far, since, ever since, presently, once, twice, thrice etc. and in the following cases:
(a) To express an action that has been recently completed.
I have just received the letter.