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

Q: Water contains 3 atoms.

A: How many atoms does water contain?
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Q: Air quality is a measure of pollutants in the air.

A: Air quality is a measure of what in the air?
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Q: Frogs and toads eating flies event is the best example of competition between species in a pond environment.

A:
Which event is the best example of competition between species in a pond environment?
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