The new curriculum standard must be set in the national examination paper (multiple choice). Functions are interspersed in multiple-choice questions and big questions, which account for a very high proportion in the whole college entrance examination paper. The final question may also be derivatives and their applications, and the probability of functions appearing in innovative questions is also very high (if you find it difficult to learn, it is suggested to abstract them into concrete understanding, which will enable you to master and apply them faster).