1, the college entrance examination series involves many knowledge points, including arithmetic progression, geometric series and summation formula. And the knowledge points are interrelated, which requires candidates to be flexible.

2. College entrance examination series is often combined with other mathematical knowledge, such as functions and inequalities, which requires candidates to have strong comprehensive application ability.

3. The series of college entrance examination questions are changeable, sometimes the same problem needs to be solved in different ways, and sometimes different problems need to be solved in the same way, which requires candidates to respond flexibly.