选 a b c?

选 a b c? 选A,B,c. 选 a b c d 选A、B、C、D 选那一个A B C 选a,b,c,d, 选哪个；a b c a,b,c三选 选a.b.c.d. 选A B C D 速度选A,B,C |c-b|+|a-c|-|b+c|,（c |a+b|-|c| |a-c|-|b-a|+|a+c|c 选 A.a≥b≥c. B.b≥a≥c. C.b≥a≥c.D.c≥a≥b a,b,c(a [b/(a-b+c)]+[(2a+c)/(b-a-c)]-[(b-c)/(b-a-c)] 计算：a/[(a-b)(b-c)]+b/[(b-c)(b-a)]+c/[(c-a)(c-d)] b/a-b+c+2a+c/b-a-c-b-c/b-c-a