How to draw a system use case diagram? (with legend)

How to Draw a System Use Case Diagram

The requirements of all legends in this article are described as follows:
the borrowers of the system are students and teachers, and the system provides services for borrowers to query books, borrow books, and return books. Students can borrow up to 5 books, and teachers can borrow up to 20 books. When borrowing and returning books, you must first "verify the identity of the borrower". When returning books, if overdue, to pay a fine. If the book that the teacher wants to borrow has been borrowed, the teacher can also reserve the book through the book reservation service. After the reservation, the book can be borrowed first.

What is a system use case diagram: a use case diagram (English: use case
diagram) is the simplest representation of user interaction with the system, showing the relationship between the user and his related use cases. Through the use case diagram, people can understand the different types of users and use cases of the system. Use case diagrams are also often used in conjunction with other diagrams.
Source Baidu Encyclopedia

How many parts does a use case diagram consist of?

Among them, the relationship can be divided into: association, generalization, inclusion, and expansion;

• Association: the communication between the user and the use case, the arrow points to the receiver of the message;
  

• Generalization: that is, inheritance, the arrow points to the parent use case;
  

• Contains: subdivided use cases, the arrow points to the subdivided functional use cases;
  

• Extension: the extension of the use case function, that is, additional functions;