1. You can use the original question for routine training.

2. Look for excellent national high school mathematics league simulation questions: such as the window of mathematics competition magazine, middle school mathematics supplement, league simulation questions on the market for regular training.

3. In order to make the knowledge more comprehensive, you can buy a "Senior High School Mathematics League Preparation Manual" (published by East China Normal University Press and Zhejiang University Press), practice the accuracy, and check for missing parts.

One thing to add: it is not enough to win the first prize in the national league or enter the winter camp. It is necessary to practice more and try again. A better choice is a supplement to middle school mathematics, which brings together mathematical olympiad questions from all over the world.

I wish you good results in the league.