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?"
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Question: Fact: isotopes are used to determine the age of fossils.

Answer: what is used to determine the age of fossils?


Question: Fact: petroleum is formed from dead organisms over time.

Answer: What forms petroleum over time?


Question: Fact: Liverworts occupy niches in moist habitats.

Answer:
What occupies niches in moist habitats?