Given scientific fact as input, generate the question from this fact such that it can be answered from the input.

Q: Elements are pure substances that make up all matter.

A: Elements are pure substances that make up what?
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Q: The climate is defined as the temperature plus precipitation of an area over a long period of time.

A: What is defined as the temperature plus precipitation of an area over a long period of time?
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Q: A sarcomere is the smallest contractile portion of a muscle.

A:
What is the smallest contractile portion of a muscle?
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