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

Q: Gastro-esophageal sphincter sphincter is located at the stomach end of the esophagus and opens to allow the bolus to enter the stomach.

A: Which sphincter is located at the stomach end of the esophagus and opens to allow the bolus to enter the stomach?
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Q: The outer layer of the sun is made up of plasma.

A: What is the outer layer of the sun made up of?
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Q: Birds and airplanes are aerofoils found.

A:
Where are aerofoils found?
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