A:I have an English book and three notebooks.
B:I have three English books and a notebook.
蔬菜是老百姓的日常生活品,蔬菜价格关系居民生活水平,面对日益上涨的蔬菜价格,市民们各有各的买菜经验。请说明下表中买菜经验的经济学依据。
9个一是____