a,b,c全正,a/丨a丨﹢丨b丨/b﹢c/丨c丨=3
a,b,c两正一负,a/丨a丨﹢丨b丨/b﹢c/丨c丨=1
a,b,c全一正两负,a/丨a丨﹢丨b丨/b﹢c/丨c丨=-1
a,b,c全负,a/丨a丨﹢丨b丨/b﹢c/丨c丨=-3
a/丨a丨﹢丨b丨/b﹢c/丨c丨可能的值有4个,选D
a,b,c全正,a/丨a丨﹢丨b丨/b﹢c/丨c丨=3
a,b,c两正一负,a/丨a丨﹢丨b丨/b﹢c/丨c丨=1
a,b,c全一正两负,a/丨a丨﹢丨b丨/b﹢c/丨c丨=-1
a,b,c全负,a/丨a丨﹢丨b丨/b﹢c/丨c丨=-3
a/丨a丨﹢丨b丨/b﹢c/丨c丨可能的值有4个,选D