For example, you borrowed two books on Monday and returned them after reading them. On Wednesday, you borrowed 10 CD, and you didn't return it until you finished reading it. On Sunday, you borrowed three periodicals. When your reader's card is full, you can't continue to borrow books. You can't continue to borrow books until you return some books.

When the CD of books and periodicals you borrowed expires, your reader's card will be automatically locked by the system. Even if there is a surplus, you can't continue to borrow books until you have returned the overdue books and periodicals.