认为是一条数轴，显然距离就是坐标差绝对值
by DAMDAM @ 2023-08-08 19:06:38
或者说，对于 $x_1=1$ , $x_2 = 2$ ,不应当认为它们之间的距离为 $0$ 吧
by DAMDAM @ 2023-08-08 19:10:49
6
by xiajiaqi @ 2023-08-10 10:29:25