Here's how it works:
* Have studied: Used for the first person singular (I), the second person singular (you), the first person plural (we), and the third person plural (they).
* Has studied: Used for the third person singular (he, she, it).
Examples:
* I have studied English for five years.
* You have studied hard for this exam.
* We have studied the history of the United States.
* They have studied abroad.
* He has studied medicine for eight years.
* She has studied art since she was a child.
* It has studied the behavior of animals.