I is generally taken as plural (due to some English rule), thus it is always I have, I had...Not I has...

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There are some English grammar rules and according to these rules has is used with second and third person. For eg.----->He has completed his homework neatly........ She has been practicing since morning............ And according to English Grammar rules only have is used with First person. For eg.---> I have completed my work on time.
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