题目

如图：在数轴上A点表示数a，B点示数b，C点表示数c，b是最小的正整数，且a、c满足|a+4|+（c﹣9）2＝0. （1） a＝，b＝ ，c＝； （2） 若将数轴折叠，使得A点与C点重合，则点B与数 表示的点重合； （3） 点A、B、C开始在数轴上运动，若点A以每秒1个单位长度的速度向左运动，同时，点B和点C分别以每秒2个单位长度和4个单位长度的速度向右运动，假设t秒钟过后，若点A与点B之间的距离表示为AB，点A与点C之间的距离表示为AC，点B与点C之间的Paul Lucas can often be seen walking around the city of San Francisco. Sometimes people are surprised to see him walking  16  any shoes or socks,  17  Lucas doesn’t mind at all.  18  likes to walk barefoot, and so do 640 other members of Dirty Sole Society, the club that Lucas  19  (start) years ago. Lucas’ idea for this is to encourage others to live  20  (free) --- free of shoes. According to Lucas, the barefoot life has many advantages.  21   most important is simply that it feels good. He also says  22  walking barefoot allows you to experience the world directly by touching it with your feet.  23  addition, the feet do not smell so much because they stay dry,   24  (make) it hard for bacteria to grow. And, of course, walking barefoot keeps your feet in good shape, so it’s actually   25  (healthy) than wearing shoes.