I have, you have, he/she has.
Present perfect tense and present perfect continuous tense.
Have and has are used in the present perfect tense and the present perfect continuous tense.
Am is the present tense, first person singular conjugation of be. The present perfect tense of be is have/has been.
The present perfect forms are have applies and has applied.Examples:We have applied for the permit. (plural subject)He has applied for the permit. (singular subject)
The present perfect forms are have been and has been.Examples:We have been to Italy. (plural subject)He has been to Italy. (singular subject)
The present perfect forms are have taught and has taught.Examples:They have taught me the basics. (plural subject)He has taught me the basics. (singular subject)
Has is the third person singular conjugation of have.The present perfect tense of have is: I/You/We/They have hadHe/She/It has had
The present perfect forms are have met and has met.Examples:We have met with the producers. (plural subject)She has met with the producers. (singular subject)
The present perfect forms are have solved and has solved.Examples:They have solved the equation. (plural subject)He has solved the equation. (singular subject)
No, "begun" is not a present tense verb. It is the past participle form of the verb "begin" and is used to create past perfect or present perfect tense. The present tense of "begin" is "begins" (third person singular) or "begin" (first/second person singular and all plural forms).
Present Perfect Tense: I have; You have; he, she, it has; we have, you have, they have Past Perfect Tense: I had; you had; he, she, it had; we had; you had; they had Future Perfect Tense: I shall have; you will have; he, she, it will have; we shall have; you will have; they will have Note: has is used in the third person, singular present perfect tense.
The present perfect forms are have solved and has solved.Examples:They have solved the equation. (plural subject)He has solved the equation. (singular subject)