In this task, you're given an open-domain question. Your task is to provide an answer to the given question. There is only one unique answer for each question. Your answer should be short, and refer to an entity, date, number, etc. Do not put your answer in the context of a sentence.

Q: What is the si unit of time period?

A: second
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Q: What school is educating greater manchester set in?

A: Harrop Fold School
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Q: How old do you have to be to buy tabacco in nevada?

A:
21
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