I recommend buying synchronous exercises. This book is closely related to the textbook, and there is an in-depth version of the textbook with 1~2 questions at the bottom of each page. Of course, if you want to be better at math than others, I think you can also buy sprint 100. This topic is difficult, but the general exam content is in this book. There is also the third grade, and I have to start to contact the Olympic Mathematics. I recommend buying the book "Draw inferences from one instance", which has two versions, A and B, and is a complete set. A is mainly an example, and B is an exercise. If you finish reading this book and understand it, it can pave the way for your future mathematics, and it is also good for key middle school exams. I wish you success and go up a storey still higher! ! ! !

If you don't understand, you can continue to ask questions. If you can, please choose a satisfactory answer. Thank you! ! !