Given a statement, generate a question such that the answer is contained in that statement.

Q: Frigidaire and Kenmore models are used for cooling food

A: What models are used for cooling food?
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Q: navigation requires knowing north, south, east or west

A: What does navigation require?
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Q: ice ages buried Earth in permafrost for millions of years at a time

A:
How many years have ice ages buried Earth in permafrost?
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