The backbone is one of the bones in the human body. 脊柱是人身体里的骨头之一。

　　It supports people's backs. 它支撑着人的背部。

　　Without a backbone, people cannot stand up, sit down or walk. 要是没有脊柱，人就不能站立、坐下和行走。

　　It is one of the most important bones in the human body. 它是人身体里最重要的骨头之一。

　　It is also called a "spine". 它也被称为“脊椎”。

　　Do you know how a backbone is formed? 你知道脊柱是怎样构成的吗？

　　It is made of many small bones. 它由很多小块骨头组成。

　　There are usually 29 small bones in the backbone. 脊柱里通常有29块小骨头。