1. If there is p=q, q=p, then p is both a sufficient condition and a necessary condition, abbreviated as p, abbreviated as p = q..

2. In order to understand the meaning of classical probability, we will use two counting principles and the basic formula of permutation and combination to calculate the probability of classical probability.

3. To find the linear equation with known points and slopes: we must master the inclination, point inclination and general equation of a straight line.

4. Understand the concepts of population and sample, and the basic methods and applications of simple random sampling, systematic sampling and stratified sampling.

5. Master the signs of trigonometric function values of angles in each quadrant and trigonometric function values of special angles such as 0, 30, 45, 60, 90,180, 270 and 360.