题目

某校七年级学生准备去购买《英汉词典》一书，此书的标价为20元，现A，B两书店同有此书出售，A店按如下方法促销：若只购1本则按标价销售，若一次性购买多于1本，但不多于20本时，每多购1本，每本售价在标价的基础上优惠2%(例如买两本，每本售价优惠2%；买3本每本售价优惠4%，依此类推)，若多于20本时，每本售价为12元；B书店一律按标价的7折销售． (1)试分别写出在两书店购此书总价yA，yB与购书本数x之间的函数关系式； (2)若某班一次性购买多于听对话，选择正确答案。 1. Did John win the football match yesterday? [     ]A. Yes, he did.B. No, he didn't. C. I don't know. 2. What's Mike's favorite sport? [     ]A. Table tennis. B. Football. C. Tennis. 3. Who will be in the match next Monday? [     ]A. John. B. Mike. C. Both of them.