It sounds like you're describing the process of healing that occurs after stubbing a toe. Here's how you can fill in the blanks:
- bone or toe (referring to the area that might be injured)
- cells (referring to the cells involved in the healing process)
- closes (referring to the process of the wound healing)
So the completed passage could read:
"Have you ever tripped while walking and stumped your toe? Sometimes this can leave a bruise or even a break. When this happens, your body immediately goes to work to build and repair the damaged bone and surrounding tissue. Over time, the wound closes up and fresh skin forms in its place."
Let me know if you have any other questions or need further information!