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 are freshmen called at the air force academy?

A: Fourth class cadets
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Q: What is the si unit of time period?

A: second
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Q: What is it called when two letters are joined together?

A:
Orthographic ligature
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