Given scientific fact as input, generate the question from this fact such that it can be answered from the input.
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Question: An object attached to a spring sliding on a frictionless surface is an uncomplicated type of simple harmonic oscillator.

Answer: An object attached to a spring sliding on a frictionless surface is an uncomplicated type of what device?


Question: Urea is made in the liver and excreted in urine.

Answer: What is made in the liver and excreted in urine?


Question: Secondary pollutants form from chemical reactions that occur when pollution is exposed to sunlight.

Answer:
Secondary pollutants form from chemical reactions that occur when pollution is exposed to what?