一、要点解读1.定义:对命题“若p,则q”而言,当它是真命题时,p是q的充分条件,q是p的必要条件;当它的逆命题为真时,q是p的充分条件,p是q的必要条件;两种命题均为真时,称p是q的充要条件.2.在判断充分条件及必要条件时,首先,要分清哪个命题是条件,哪个命题是结论;其次,结果要分四种情况说明: First, the point of interpretation 1. Definition: For proposition “If p, then q ”, when it is true proposition, p is a sufficient condition of q, q is a necessary condition of p; When its inverse proposition is true , Q is a sufficient condition for p and p is a necessary condition for q. Both propositions are true, and p is a necessary and sufficient condition for q. 2. When judging sufficient conditions and necessary conditions, first of all, we must distinguish which proposition Is the condition, which proposition is the conclusion; Second, the results should be divided into four cases: