Given scientific fact as input, generate the question from this fact such that it can be answered from the input.
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Question: Elements are pure substances that make up all matter.

Answer: Elements are pure substances that make up what?


Question: Line graphs are especially useful for showing changes over time.

Answer: Line graphs are especially useful for showing changes over what?


Question: A carbon atom with 6 protons and 8 neutrons is more specifically known as carbon 14.

Answer:
A carbon atom with 6 protons and 8 neutrons is more specifically known as?