(1)试判断a,b,c的正负性;
(2)根据数轴化简:
①|a|=_____; ②|b|=_____:
③|c|=_____; ④|-a|=_____;
⑤|-b|=_____; ⑥|-c|=_____.
(3)若|a|=5.5,|b|=2.5,|c|=5,求a,b,c的值.
(1)比较大小:b____0, a____c, b____c, b-a____0;
(2)A,B两点间的距离为__________,B,C两点间的距离为_______;
(3)化简:|b|-|b+c|+|c-a|-|a+c|-|b-c|.