Your skeleton is completely replaced roughly every 10 years.
Why it is true
Bone is living tissue. Old bone is constantly broken down by cells called osteoclasts and rebuilt by osteoblasts, meaning you literally have a new skeleton.
Source: Biology
Would you rather be asked first?
This is the reading side of the site, so the answer is in the sentence above — that is the whole point of it. Test yourself works the other way round: the question comes on its own, and the fact and the explanation only appear once you have answered.