If it is done, but it is difficult, I suggest you see how the answer is solved, whether it provides different ideas or solutions, sum up and expand your ideas.
If you are free, you can prepare a notebook, extract all the good questions and wrong questions, and review them later to see if you can do it again.
However, if the title of your book is better and you take it as seriously as I do, I think you will make progress. Come on! If your foundation is weak, I suggest you don't do difficult problems and digress, because this will only get twice the result with half the effort. )
Handmade, hope to adopt, thank you!