There are some difficult questions in the compulsory mathematics questions in the college entrance examination, which require candidates to have high mathematical thinking ability and problem-solving skills. Here are some challenges:

1. Functions and equations: Functions and equations are important contents of high school mathematics, involving the properties of functions, images, solutions of equations, etc. Among them, the compound and inverse function of functions, the maximum value of quadratic functions and the image transformation of trigonometric functions are all difficult to understand and master.

2. Series and mathematical induction: Series is the basic content of high school mathematics, involving arithmetic progression, geometric progression, recursive series, etc. Mathematical induction is a proof method, which requires candidates to have strong logical thinking and reasoning ability.

3. Probability statistics: Probability statistics is an important content of high school mathematics, involving the calculation of probability, the probability of events, the probability distribution of random variables and so on. Among them, binomial distribution, normal distribution and conditional probability are all difficult to understand and apply.

4. Analytic geometry: Analytic geometry is an important part of high school mathematics, involving the positional relationship between straight lines and circles, and the relationship between plane and space. Among them, the intersection of straight lines and circles and the distance between plane and space are difficult to understand and solve.

5. Derivative and differential: Derivative and differential are important contents of high school mathematics, involving the derivation and application of functions. Among them, the calculation and application of derivative are difficult to understand and solve.