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

Q: Water can be boiled to kill giardia and most other pathogens.

A: Water can be boiled to kill giardia and most other what?
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Q: Fractional crystallization is the separation of compounds on the basis of their solubilities in a given solvent.

A: What is the separation of compounds on the basis of their solubilities in a given solvent?
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Q: Elements are pure substances that make up all matter.

A:
Elements are pure substances that make up what?
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