In cases where it happened in the past, the exact time is unknown.
I have listened that music hundred times.
There have been many earthquakes in my country.
Actions that took place in the past and are still ongoing
I have had a cold for two weeks.
Martina has been in Germany for six months.
Actions that took place in the past, the consequences of which are still ongoing
I have lost my key
I have studied in Bachelor.
Declarative sentence have/has+ past particle. The past particle form of the verb is constructed by adding the suffix ed to the end of the verb when the verb is regular. When the verb is irregular, the past particle form is constructed in a special way. It is necessary to memorize the past particle form of such irregular verbs. I have finished my work. She has cooked dinner. We have spent three years in Belgium.
Question In the question sentence have/has comes to the beginning of the sentence. Has she cooked dinner? Have you spent three years in Belgium?
Negation In the negation sentence after have/has not will be used. I have not finished my work. She hasn’t cooked dinner.