题目有没有漏掉什么呢?如果题目是：2/11×13＋2/13×15＋2/15×17+2/17×19用列项法2/11×13＋2/13×15＋2/15×17+2/17×19=2/11-2/13+2/13-2/15+2/15-2/17+2/17-2/19=2/11-2/19=2(19-11)/11×19=16/209...