“或”与“且”属逻辑联结词,是初中数学不加定义却经常使用的概念,学生使用时常因概念混淆导致错误.下面举例说明“或”与“且”的正确使用方法.一、或表示选择关系在数学中含或此、或彼、或两者三种选择,ab=0 a=0,或b=0 a,b至少有一个为0.例1若|x|+2=4,则x=()(A)-2(B)2(C)-2且2(D)-2或2解|x|=2,x=-2或2,应选D. “Or ” and “and ” are logical conjunctions, which are often used without definition in junior high school mathematics. Students often use concepts to be confused to cause mistakes. The following example illustrates that “” or “and ” and A, or that the choice of relations in mathematics with this or, or, or both options, ab = 0  a = 0, or b = 0  a, b at least one of 0 . Example 1 x | () -2 (B) 2 (C) -2 and 2 (D) -2 or 2 solution | x | = 2, x = - 2 or 2, should choose D.