This offer can be used unlimited times a year, but a series of products can only be bought once.

In order to ensure the fairness and effectiveness of educational concessions, allowing users to purchase the same series of products many times will lead some users to abuse the concessions, or some users will get more concessions through multiple purchases, which will cause unfair competition to other users.

In order to maintain the fairness and effectiveness of educational concessions, users are only allowed to buy the same series of products once a year.