题目

A.He likes dancing. B.He doesn’t like music.C.He is a modern type of man. D.He is particular about dancing music. 答案：【答案】D【解析】【原文】此题为听力题，解析略。若x，y满足约束条件目标函数z＝x＋2y最大值记为a，最小值记为b，则a－b的值为________．