As for the big problem, it involves a process of deepening the problem. First of all, you should learn to summarize information and learn to extract problems from it. When you see the information, you can probably know what to ask next. I suggest you do all the big questions in the comprehensive paper of college entrance examination in your province in recent years. Do it yourself first, then compare the answers to see if there is any problem with your own thinking, or ask the teacher for advice. It is very important to summarize the answering methods from the real questions. In addition, it is best to do the questions in the order of the examination papers. Don't do what you want to do first, and don't get stuck on the big questions you can't do for too long, delaying the answers later.