1, the foundation is not solid. In fact, mathematics is a subject that can never be learned without a good foundation. Engineering with a solid foundation is more important to mathematics than liberal arts.
For example, ask a high school student a question: What is 12x5? People will say, that's easy, when I'm a fool!
Yes, he thinks it's simple. When I was in the second grade of primary school, I found the relevant documents of 15 for you at an early age. Is it simple? Why is the topic of doing primary school in middle school so simple? Because of a lot of content learned in senior grades and junior high schools, I unconsciously learn the content of junior grades over and over again. For example, high school students' solving one-dimensional linear equations is completely pediatrics, and beginners certainly don't think so.
The same study time, or even less time, upstream students learn more and faster than downstream students, one of the important reasons is that the foundation is different. Therefore, the author wants to say that all the topics are expressions of basic concepts, and the comprehensive questions only contain more basic concepts and basic formulas.
Only when you have a solid understanding of the context and usage of basic concepts and formulas can you know the true face of the topic like the back of your hand and answer it accurately.
2, greed is not digested, many students have always mistakenly thought that as long as you do a lot of problems, your math scores will be good. Many parents will buy back many problem sets for their children to do. The school teacher also distributed a large number of test papers for the children to complete. But many people invest a lot.
3, can't tell the difference between important topics and unimportant topics. Those topics that are directly related to important concepts are important topics, while those that have little to do with important concepts and need special skills to solve them are not so important topics.
Therefore, in each unit, those themes that should be combined with Tong Jia are important purposes. We don't spend time firmly grasping important topics, but spend most of our time and energy on unimportant topics, so that we will find mathematics more and more difficult.
I don't know my level. Without a good person to do difficult problems, it is tantamount to climbing a mountain with luggage that can't be carried at all. If you study beyond your level, because you can't do what you can, math learning will become a burden. Once you lose interest, it's too difficult to get it back.