中轴骨
The mollusc phylum includes all soft-bodied animals without backbones. 软体动物门包括所有无脊椎的软体动物。
Who will win the battle for the backbones? 谁能赢得主干网之战?
Only two backbones， a thousand ribs. 只有两根脊椎，却有很多肋骨。
Simply adding bandwidth to the Internet backbones is not an answer. 只是简单的在互联网骨架上增加带宽是应付不了的。
They are vertebrates,that is,animals that have backbones. 它们是脊椎动物，即有脊骨的动物。
