Sets and simple logical sets have four properties. You can determine the elements in a generalized set. The elements in a deterministic set must be determined. For example, a good student does not have this attribute because its concept is vague. The elements in an anisotropic set must be unequal to each other, and one element cannot be repeated. Elements in an unordered set are independent of order. This is a key point, but it's hard to say. We should do special training, such as quadratic function, exponential logarithmic function and so on. When doing this kind of problems, we should master several function ideas, such as constructor, combination of function and equation, symmetry idea, transformation elements, etc. This is also an important question type. When doing the body, we should have a whole idea, replace it as a whole, separate arithmetic from arithmetic, pay attention to the connection, so as to do it well, and observe the form of the series to judge what it is. It is also necessary to master several methods of finding the sequence of derived formulas, as well as summation formulas and summation methods, such as elimination and split term method, dislocation subtraction method, formula method, grouping summation method and so on. Trigonometric function is not an examination question, but an applied knowledge point, so just memorize the trigonometric function value of a special angle and some important theorems to make a five-plane vector. This is a relatively abstract difficulty in the combination of geometry and algebra, and it is necessary to have skills when combining. The main thing is to master the basic knowledge in place and pay attention to expansion. When you get married, you can do more questions, see more questions and have ideas, which can simplify the problems and help improve the efficiency of doing them.