Turn the given fact into a question by a simple rearrangement of words. This typically involves replacing some part of the given fact with a WH word. For example, replacing the subject of the provided fact with the word "what" can form a valid question. Don't be creative! You just need to rearrange the words to turn the fact into a question - easy! Don't just randomly remove a word from the given fact to form a question. Remember that your question must evaluate scientific understanding. Pick a word or a phrase in the given fact to be the correct answer, then make the rest of the question. You can also form a question without any WH words. For example, "A radio converts electricity into?"

[Q]: Fact: liquid propane is used to expand hot air balloons.
[A]: How is liquid propane used in hot air ballooning?


[Q]: Fact: a tumor can be burned away when an electrical circuit is working properly.
[A]: When the electrical circuit is working properly, what can happen?


[Q]: Fact: Breaks in the bone heal when osteoclasts form new bone.
[A]:
How do breaks in the bone heal?