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

Q: Cancer occurs most often in adults over fifty age.

A: Cancer occurs most often in adults over what age?
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Q: Urea is made in the liver and excreted in urine.

A: What is made in the liver and excreted in urine?
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Q: The passenger piegon once most common bird in north america became extinct in the 1800s.

A:
What once most common bird in north america became extinct in the 1800s?
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