填空题
Our bodies are similar in many ways. We may not look exactly alike, but our body shapes are more or less the same. Our bodies are made up of several parts—the head, neck, trunk, arms and legs. These parts are held together by a framework called the skeleton. The skeleton is made up of bones. We cannot see our bones because they are covered by our muscles and skin. However, we can feel them.
The bones of our body are hard, white and strong. They are not easily broken. If a bone is broken, you will see a soft brownish-red part in the center. This part is called the bone marrow. It makes the red and white cells of blood. More and more cells are formed until finally the broken ends meet and join together.