近年来国内外数学考试或竞赛中出现的选择题,引起了教师和学生们的广泛注意。比如一九八一年高考题(理工农医类)第三题,要求在表中所列各小题中,指出A是B的充分条件,还是必要条件,还是充要条件,或者都不是,就是一道选择填空题。八一年二十五省、市、自治区数学竞赛试题 In recent years, multiple choice questions appearing in mathematics examinations or competitions at home and abroad have attracted extensive attention from teachers and students. For example, in the first question of the 1981 college entrance examination (science and technical agronomy and medicine) category, it is required to indicate that A is a sufficient condition or a necessary condition for B, or a sufficient or necessary condition, or neither, in each of the small items listed in the table. It is a matter of choosing blanks. Twenty-five provinces, cities and autonomous regions mathematics competition test questions